JPH037379A - Optical recording medium - Google Patents

Abstract

PURPOSE:To increase crystallization speed during information deletion and improve the preservation of an amorphous state of recorded information by specifically modifying Ge-Sb-Te material. CONSTITUTION:An optically recording medium consists of a recording layer which indicates a change due to irradiation with light on a substrate and stores, retrieves and deletes information based on the change. The recording layer has a composition shown by formula I where Z is either one of Au, Cu, CO or Ni. In the formula I, X is molar fraction and Y is mol%. Thus it is possible to obtain an optical recording medium capable of high crystallization speed during deletion and also high preservability of an amorphous state or recorded information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording layer of an optical recording medium, and more particularly to a rewritable optical recording medium that can be erased at high speed and has good preservation of recorded information.

[Conventional technology]

In recent years, there has been an increasing demand for higher density and larger capacity information storage, and research and development has been actively conducted both domestically and internationally.
In particular, optical disks that use a laser as a light source have a recording density approximately 10 to 100 times that of conventional magnetic recording media, and can record information without contact between the recording/reproducing head and the recording medium.

Because it can be played back, there is little damage to the recording medium and it has a long lifespan, so it can record a huge amount of information.
It is promising as a high-density, large-capacity recording method for playback.

These optical discs can be roughly divided into three types, read-only type and rewritable type, depending on the purpose.

The read-only type is a read-only disk from which information can only be read, and the write-once type allows information to be recorded and reproduced as needed, but recorded information cannot be erased. On the other hand, the rewritable type is capable of recording and reproducing information, as well as erasing and rewriting already recorded information, and is desired and has the highest expectations for use as a data file for computers.

Regarding rewritable disks, two recording methods are being developed: magneto-optical and phase change, but both methods still have room for improvement in terms of recording materials, writing mechanisms, etc. . Among these, the phase change method generally focuses a laser beam on the recording surface of the disk, heats it, and controls the pulse output and pulse width of the laser beam, thereby changing the phase of the recording material, that is, from a crystalline state to a non-crystalline state. It causes a transition to a crystalline state or a phase transition, and records and erases information based on the difference in reflectance in each state.

The structure of this phase change type optical disk is omitted from illustration, but usually a protective film made of ceramic such as Z-port S is formed on the surface of a substrate made of polycarbonate or the like, which has many tracking grooves, and then recording is performed on the surface of the substrate. It has a structure in which a recording material, that is, a recording layer is provided, and a protective film made of ceramic or the like and a surface protective film of an organic substance are sequentially deposited thereon. In addition, a cooling film such as HEN is provided between the protective film and the organic substance surface protective film. The cooling film is for increasing the cooling rate from the molten state during the change from the crystalline state to the amorphous state, and in this case, the ceramic film acts as a heat insulating layer. In order to ensure the characteristics of the medium, it is important to optimize the thickness of this heat insulating layer. The radar light is normally incident on the substrate from the opposite side to the side on which the recording layer is provided.

Many materials are considered promising materials for phase change optical recording media because they have relatively high stability. In particular, a material with a composition expressed as (GeTe) There is.

In a normal optical disc, the optical recording material is in a crystalline state in the initial state, and when recording information, it is irradiated with a laser to melt the irradiated area and then rapidly cooled, making it sufficiently stable without crystallization. As in, it returns to the crystalline state.

[Problem to be solved by the invention]

However, according to our study results, this material had the following problems. That is, as mentioned above, the recording layer is in the crystalline state during writing, and the crystalline state is inherently more unstable than the crystalline state, and the storage life when information is stored for a long time becomes a problem. Become. For example, Ge5b2
Te4 [= (GeTe) disappeared in 50 hours at a temperature of 100°C. In order for information written on a recording medium to be stable for more than 10 years at 50℃, for example, a temperature of 300-1 at 100℃ is required.
A lifespan of 1,000 hours is required. Furthermore, the current mainstream recording method is a bit position recording method that determines the presence or absence of a bit, but a bit edge recording method that makes the edge of a bit correspond to a recording point is promising in the future. In this bit edge recording method, the number of bits is reduced.This invention was made in view of the above points, and its purpose is to
The object of the present invention is to provide an optical recording medium that has a high crystallization speed when erasing information and has excellent non-state storage performance that is filled with recorded information by improving -Te-based materials.

[Means to solve the problem]

According to the present invention, the above-mentioned object is to irradiate a recording layer on a substrate with light and record and reproduce information based on changes in the light.

In optical recording media for erasing, Z is Au, Cu,
Co.

When any one of Ni is used, the general formula % formula % (
1) A recording layer having a composition represented by: 2) Z
is Cu, and y satisfies the following formula % formula % (2). 3) The recording layer on the substrate is irradiated with light, and the changes in the optical recording medium are used to record, reproduce, and erase information. Te, Gef
When the composition of alTe~1sblcl is expressed in triangular coordinates, point A (Ge,,Sb,Te,.), point B (GeS
b2Tess) 1 point C (Ge2Sb2Teaa) 1
Point D is in the area surrounded by (Ge4oSb@Tll!s, *), and when W (mol%) satisfies the following formula 9% (3), the general formula [Ge+a+Tecb+Sb+
c+], o, -.

This is achieved by providing a recording layer having a composition represented by [Cu].

[Effect]

When Au, Cu, Co, or N1 is added to Ge-3b-Te-based materials, the crystallization temperature becomes high.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

(Example 1) The thin film of the optical recording medium of the present invention can be easily produced by ordinary RF magnetron sputtering.

ZnS on a polycarbonate disk substrate.

(Ge2St12↑as)s4Au,, ZnS,
A Spar/9 film was formed in the order of kl. The thickness of each film is 12Or++n, 60%m.

170n111.1100n. The disk diameter is 1
It is 30mm. Ge2SJTes (GeTe) 2
(Sb2Tea).

While rotating this disk at a circumferential speed of 11 m/s, a laser beam having a wavelength of 380n+e and an output of 8a+Il was irradiated.

The laser spot diameter on the disk surface was approximately 1 μm.

The optical recording material film immediately after sputtering was in an amorphous state and had a light reflectance of about 15%, but the light reflectance increased to about 38% by the above laser irradiation.

When the same location on the disk was irradiated with the laser again under the same conditions, no change was observed in the reflectance from 38%. The reason why the reflectance changed from 15% to 38% is because the optical recording film changed from an amorphous state to a crystalline state, and the reason why the reflectance did not change after the second laser irradiation was due to the first laser irradiation. This indicates that crystallization was sufficient.

In order to confirm the above fact, a similar recording layer was formed on a glass substrate, and changes in reflectance were measured while increasing the temperature at 10° C./win. The results are shown in FIG. Reflectance is 1
The temperature was rising around 85℃. When the crystal morphology of the recording layer was examined by X-ray diffraction before and after this, the recording layer was crystallized after the reflectance increased, and the crystal was mainly Ge2S.
b2Te was observed.

The reflectance values almost corresponded to the values for the optical discs described above, and it was confirmed that the reflectance changes in the optical discs were due to crystallization of the recording layer.

Regarding erasing after writing information, it was possible to erase at a circumferential speed of 11 n/s as described above.

That is, after the above optical disc has been sufficiently crystallized, when writing is performed using pulsed power with a laser output of 15 mW and a frequency of 3.7 MHz, the playback output of the optical disc is 47 d in CN ratio.
The value of B was obtained, but if this is erased under the above conditions, it becomes C
The N ratio decreased at about 15 dat and was almost completely eliminated.

The relationship between the erasing time and the Au content in the recording layer is shown in Figure 1. When the amount of ^1 added is less than 10%, the erasing time hardly changes, but when it becomes more than 10%, it increases. , exceeds 100ns at 15%, peripheral speed 1111/S
It becomes difficult to erase records. l1m8 has a diameter of 1301
This is the circumferential speed at the outer periphery when an 11m disc is rotated at 1800rpa + closed, and if erasing cannot be done under these conditions,
This poses a practical problem. On the other hand, the above-mentioned 10℃ 7m
The crystallization temperature measured by the change in reflectance during the heating process at in, increases as the ^U content increases, as shown below, and reaches approximately 187°C at a ^U content of 118%.

This high crystallization temperature means that the amorphous spot written on the optical disc has high thermal stability. In addition, the number of repetitions of writing and erasing is observed to increase when 3% is added, but it tends to decrease when the amount exceeds 12%, and when the amount added is more than 15%, the number of repetitions becomes so small that it becomes a practical problem. Become. This is presumed to be because the recording material composition deviates greatly from the compound composition, resulting in local segregation as the process is repeated.

Table 1 Table 1 also shows the activation energy (Ea) for crystallization, which was determined by the Kirasinger plot method while changing the heating rate in differential thermal analysis. Ea increases significantly with the addition of Au.

A large Ea is a factor in achieving both high-speed erasing and stability of an amorphous spot of recorded information at room temperature. Ea reaches its maximum when the Aui addition is 8%, and decreases slightly above that.

Figure 3 shows (GeTe) X (Sb2Te3) l-
K (Curve 31A) and the composition (X value) dependence of the crystallization temperature when 5% of ^U is added thereto (Curve 32A). It can be seen that the addition of ^U increases the crystallization temperature and improves the stability.

80℃, 1000℃ to confirm stability near room temperature
Figure 4 shows the results of an accelerated test by standing for a certain period of time.

^The CN ratio of the optical disk medium using Ge5b2Te4 without U addition (curve 41A) is approximately 4 after being left for 500 hours.
Although it showed a decrease in dB, (GeSb2Te4) 94^
The CN ratio of the optical disk medium using US (curve 42A) hardly decreased even after being left for 1000 hours, showing good characteristics.

(Example 2) The thin film of the optical recording medium of the present invention can be easily produced by ordinary RF magnetron sputtering.

ZnS on a polycarbonate disk substrate.

(Ge2Sb2Tes)s*cu@, ZnS, A
Sputtered films were formed in the order of j'. The thickness of each film is 120 nm and 60 nm, respectively.

17Or+11+, 1100n. The disk diameter is 13001111. [Ge2Sb, Te, =
(GeTe) 2(Sb2Te, )] While rotating this disk at a circumferential speed of 11+n/s, a wavelength of 830r+m
, a laser beam with an output of 811111 was irradiated. The diameter of the Radespot on the disk surface was approximately 1 μm. The optical recording material film immediately after sputtering was in an amorphous state and had a light reflectance of about 17%, but the light reflectance increased to about 38% by the above laser irradiation. When the same location on the disk was irradiated with the laser again under the same conditions, no change was observed in the reflectance from 38%. The reason why the reflectance changed from 17% to 38% is because the optical recording film changed from an amorphous state to a crystalline state.The reason why the reflectance did not change after the second laser irradiation was because the first laser irradiation This indicates that crystallization was sufficiently performed.

In order to confirm the above fact, a similar recording layer was formed on a glass substrate, and the change in reflectance was measured while increasing the temperature at 10° C./min. The results are shown in FIG. The reflectance increased around 192°C. When the crystal morphology of the recording layer was examined by X-ray diffraction before and after this, it was found that the recording layer was crystallized after the reflectance increased, and the crystal was mainly composed of G.
e2Sb2Te was observed.

The reflectance values almost corresponded to the values for the optical disc, and it was confirmed that the change in reflectance on the optical disc was due to crystallization of the recording layer.

Regarding erasing after writing information, it was possible to erase at a circumferential speed of 11 m/s, similar to the above.

That is, after the above-mentioned optical disc has been sufficiently crystallized, when a pulse input with a frequency of 3.7 MHz is written with a laser output of 15al-, the reproduction output of the optical disc has a CN ratio of 48
A value of dB was obtained, but when this was erased under the above conditions, the CN ratio decreased to about 17 dB, and it was almost completely erased.

The relationship between the erasing time and the Cu content in the recording layer is as shown in Figure 5. When the amount of Cu added is less than 15%, the erasing time hardly changes, but when it exceeds 15%, it increases. At 20%, it exceeds 1 oons, making it difficult to erase records at the circumferential speed If/s. lbn/s is 130mm in diameter
This is the circumferential speed at the outer periphery when the disk is rotated at 1800 rpm, and if erasing cannot be performed under these conditions, it will be a problem in practice. On the other hand, the aforementioned 10°C/min
The crystallization temperature measured by the change in reflectance during the heating process increases as the Cu content increases, as shown below, and reaches about 197°C at a Cu content of 10%.

This high crystallization temperature means that the amorphous spot written on the optical disc has high thermal stability. In addition, the number of repetitions of writing and erasing is observed to increase when 3% is added, but it tends to decrease when the amount is more than 15%, and when the amount added is more than 20%, the number of repetitions becomes so small that it becomes a practical problem. Become. This is presumed to be because the recording material composition deviates greatly from the compound composition, resulting in local segregation as the process is repeated.

Table 2 Table 2 shows the activation energy (Ea) of crystallized tElc determined by the Kissinger plot method by changing the heating rate of differential thermal analysis.
was also shown. Ea increases significantly with the addition of Cu.

A large Ea is a factor in achieving both high-speed erasing and stability of an amorphous spot of recorded information at room temperature. Ea reaches a maximum when the amount of Cu added is 10%, and decreases slightly above that amount.

FIG. 7 shows (GeTe) x (Sb2Tes) l-
It shows the composition (X value) dependence of the crystallization temperature on X (curve 31B) and when 5% of Cu is added thereto (curve 32B). It can be seen that the addition of Cu increases the crystallization temperature and improves the stability.

8()'tl' to confirm stability near room temperature.
FIG. 8 shows the results of an accelerated test conducted by leaving the sample for 1000 hours. GeSb2Te* without adding Cu (curve 4
The CN ratio of the optical disk medium using (GeSbaTea) showed a decrease of about 4 dB after being left for 500 hours.
) 94CLI8 (Curve 42B) The CN ratio of the optical disk medium using 94CLI8 (curve 42B) hardly decreased even after being left for 1000 hours, showing good characteristics.

The compositional deviation from [(GeTe) Here points A, B, C,
D each is Ge4H5b@Te5o, Ge4Sb
@Te5a, Ge@Sb3°Te@4. Ge4
The composition of oSb@Te5a is shown. Figure 18 is on line AB,
Figure 19 shows Cu-doped IW on the CD line at 3.10°15.
The crystallization temperature at 20% is shown. It can be seen that adding Cu increases the crystallization temperature. Figure 20 is on the ΔB edge line. Figure 21 shows the Cu addition amount W on the CD line of 3.
10 is a diagram showing erasing time when the ratio is set to 10%, 15%, and 20%. When W is 15% or less, the erasing time hardly changes, but when W becomes 20%, it becomes about 150 ns. Points A, B, C
, D, the stability of the amorphous state at room temperature can be improved while maintaining the high speed of recording spot erasing.

(Example 3) The thin film of the optical recording medium of the present invention can be easily produced by ordinary RF magnetron sputtering.

ZnS on a polycarbonate disk substrate.

(Ge, Sb2Te, ), Co4. ZnS, M
A sputtered film was formed in this order. The thickness of each film is 1
20nm, 60%m.

170ns and 1100n. The disc diameter is 13
It is 0mm. [Ge, Sb, Tea = (GeTe
) z (Sb2Tes) ] This disk has a circumferential speed of 1I
While rotating at III/S, laser light with a wavelength of 830no+ and an output of 81 was irradiated. The diameter of the Radespot on the disk surface was approximately 1 μm. The optical recording material film immediately after sputtering was in an amorphous state and had a light reflectance of about 16%, but the light reflectance increased to about 38% by the above laser irradiation. When the same location on the disk was irradiated with the laser again under the same conditions, no change was observed in the reflectance from 38%. The reflectance changed from 16% to 38% because
This is because the optical recording film changed from an amorphous state to a crystalline state, and the reflectance did not change after laser irradiation again.
It is shown that crystallization was sufficiently performed by the first laser irradiation.

To confirm this, a similar recording layer was formed on a glass substrate, and the change in reflectance was measured while increasing the temperature at lθ°C/akin. The results are shown in Figure 1O.

The reflectance increased around 187°C. Examination of the crystal morphology of the recording layer before and after this by X-ray diffraction revealed that the recording layer was crystallized after the reflectance increased, and the crystals were mainly Ga2SbzTε. The reflectance values almost corresponded to the values for the optical discs described above, and it was confirmed that the reflectance changes in the optical discs were due to crystallization of the recording layer. Regarding erasing after writing information, it was possible to erase at a circumferential speed of 11a+/s as described above. That is, after sufficiently crystallizing the above optical disk, the laser output is 15I1w and the frequency is 3.7MHz.
When writing the pulse input, a CN ratio of 48 dB was obtained as the reproduction output of the optical disc, but when this was erased under the above conditions, the CN ratio decreased to about 13 dB, and it was almost completely erased.

The relationship between the erasing time and the CO content in the recording layer is as shown in Figure 9. When the amount of CO added is less than 8%, the erasing time hardly changes, but when it becomes more than 8%, it increases. At 10%, the time exceeds 100 ns, making it difficult to erase records at a circumferential speed of 11 m/s. l1m/s is the circumferential speed at the outer periphery of a disk with a diameter of 130 mm and a rotational speed of 180 rpm, and if erasing cannot be performed under this condition, it will be a problem in practice. On the other hand, the crystallization temperature measured by the change in reflectance during the heating process at 0°C/akin, as described above, increases as the CO content increases, and reaches approximately 190°C at a CO content of 5%. Become.

This high crystallization temperature means that the amorphous spot written on the optical disc has high thermal stability. In addition, the number of repetitions of writing and erasing is observed to increase when 2% is added, but it tends to decrease when it is more than 8%, and when the amount added is more than 10%, the number of repetitions becomes so small that it becomes a practical problem. Become. This is presumed to be because the recording material composition deviates greatly from the compound composition, resulting in local segregation as the process is repeated.

Table 3 Table 3 shows the Kissinger plot method 1 by changing the heating rate of differential thermal analysis.
Activation energy (Ea) of crystallization IT obtained from customer
was also shown. Ea increases significantly with the addition of CO.

A large Ea is a factor in achieving both high-speed erasing and stability of an amorphous spot of recorded information at room temperature. Ea reaches a maximum when the amount of CO added is 5%, and decreases slightly above that amount.

Figure 11 shows (GeTe) x (Sb2Tei) l
-X (curve 31C) and the composition (X value) dependence of crystallization temperature when 5% of CO is added thereto (curve 32C). It can be seen that the addition of Co increases the crystallization temperature and improves the stability.

80℃, 1000℃ to confirm stability near room temperature
Figure 12 shows the results of an accelerated test by standing for a period of time. The CN ratio of the optical disk medium using Ge5b2Te4 (curve 41C) without added Co showed a decrease of about 4d[] after being left for 500 hours, but (GaSbzTε*) 5
The CN ratio of the optical disk medium using -Co5 (curve 42C) hardly decreased even after standing for 100 i) hours, showing good characteristics.

(Example 4) The thin film of the optical recording medium of the present invention can be easily produced by ordinary RF magnetron sputtering.

ZnS on a polycarbonate disk substrate.

(Ge2Sb2TeS)s@Ni4. ZnS, ^l
A sputtered film was formed in this order. The thickness of each guard is 1
20nn, 60no+.

It was set to 17Qnm and 1100n. The disk diameter is 1
There are 11 30ml bottles. cce2sb2Tes = (G
eTe) 2 (Sb2Tes) ] This disk was irradiated with Raded light having a wavelength of 830 nm and an output of 8++J while rotating at a circumferential speed of 11 m/s. The laser spot diameter on the disk surface was approximately 1 μm. The optical recording material film immediately after sputtering is in an amorphous state, and its light reflectance is approximately 16%.
However, due to the above laser irradiation, the light reflectance was approximately 38
It rose to %. When the same location on the disk was irradiated with the laser again under the same conditions, no change was observed in the reflectance from 38%. The reason why the reflectance changed from 16% to 38% is because the optical recording film changed from an amorphous state to a crystalline state.The reason why the reflectance did not change after the second laser irradiation was because the optical recording film changed from an amorphous state to a crystalline state. This indicates that crystallization was sufficiently performed.

In order to confirm this, a similar recording layer was formed on a glass substrate, and the change in reflectance was measured while increasing the temperature at 10° C./sin. The results are shown in FIG.

The reflectance increased around 184°C. When the crystal morphology of the recording layer was examined by X-ray diffraction before and after this, it was found that the recording layer was crystallized after the reflectance increased, and GeaSbzTes was mainly observed as the crystal. The reflectance values almost corresponded to the values for the optical discs described above, and it was confirmed that the reflectance changes in the optical discs were due to crystallization of the recording layer. As for erasing information after writing, it was possible to erase the information at a circumferential speed of 11m8, similar to the above. That is, after sufficiently crystallizing the above optical disc,
When a pulse input with a frequency of 3.7 MHz was written with a laser output of 15a+W, a CN ratio of 48 dB was obtained as the playback output of the optical disc, but when this was erased under the above conditions, the CN ratio decreased to about 13 dB. I was able to completely erase it.

The relationship between the erasing time and the Ni content in the recording layer is as shown in FIG. At 10%, the time exceeds 100 ns, making it difficult to erase records at a circumferential speed of 11++/s. l1m/s is diameter 130+
This is the circumferential speed at the outer periphery when the rotation speed is 1800 rpm I11 with a u+ disk, and if erasing cannot be done under these conditions,
This poses a practical problem. On the other hand, the aforementioned 10℃7m
The crystallization temperature measured by the change in reflectance during the heating process at i.

This high crystallization temperature means that the amorphous spot written on the optical disc has high thermal stability. In addition, the number of repetitions of writing and erasing is observed to increase when 2% is added, but it tends to decrease when it is more than 8%, and when the amount added is more than 10%, the number of repetitions becomes so small that it becomes a practical problem. Become. This is presumed to be because the recording material composition deviates greatly from the compound composition, resulting in local segregation as the process is repeated.

Table 4 Table 4 also shows the activation energy (Ea) of the crystallization port, which was determined by the Kirasinger plot method while changing the heating rate of the differential thermal analysis. Ea increases significantly with the addition of Ni.

A large Ea is a factor in achieving both high-speed erasing and stability of an amorphous spot of recorded information at room temperature. Ea reaches its maximum when the Nil content is 5%, and decreases slightly above that level.

Figure 15 shows (GeTe) w (Sb2Tes) l
-X (curve 31D) and the composition (X value) dependence of the crystallization temperature when 5% Ni is added thereto (curve 32D). It can be seen that the addition of Nil increases the crystallization temperature and improves the stability.

To confirm stability near room temperature, the temperature was 80℃ and 100℃.
Figure 116 shows the results of an accelerated test conducted by allowing the sample to stand for 0 hours. Ge5b, Te, without adding Ni (curve 41D
) The CN ratio of the optical disk medium using (GeSb2Te4)s showed a decrease of about 4dB after 500 hours of exposure.
The CN ratio of the optical disk medium using 4N+6 (curve 42D) hardly decreased even after being left for 1000 hours, indicating good characteristics.

〔Effect of the invention〕

According to the present invention, 1) in an optical recording medium in which a recording layer on a substrate is irradiated with light and information is recorded, reproduced, and erased by changes in the light, 2 is A;
A recording layer having a composition represented by the general formula % formula % (1) when u, Cu, Co or N1 is provided, in which case (X in formula (1)
represents the mole fraction, and y represents the mol%. )-W[Cu]W, and y satisfies the following formula % formula % (2) 3) Optical recording that records, reproduces, and erases information by irradiating the recording layer on the substrate with light and changing the light. In the medium, Ge
talTe (When the composition of blsb ta+ is expressed in triangular coordinates, point A (Gem+5l)sTeso) 1
Point B (GesSb, 1aTes3) 1 point C (Ge, S
b,,Te@, ), is in the region surrounded by point D (Ge4oSb@Te54), and when W (mol%) satisfies the following formula 0% (3), the general formula [Ge talTe (bls
b Fell+oo-w [Cu]w Since the recording layer has a composition expressed by w, the crystallization temperature is high, the crystallization speed during erasing is fast, and the storage performance of the amorphous state that is recorded information is also excellent. An optical recording medium is obtained.

[Brief explanation of drawings]

Figure 1 shows (GeiSbzTei) l 011-yA
Diagram showing the relationship between the composition (y value) of u and erasing time, second
The figure is a diagram showing the change in reflectance when (Ge. 5b2Tes) as^u6 is heated at 10°C/+in.
GeTe) x (Sb, Tea)1-0] 5sAI
Figure 4 is a diagram showing the relationship between the composition (X value) and crystallization temperature in Is in comparison with the conventional one.
Temperature of optical recording medium using e,)s, Au, 80℃
Figure 5 is a diagram comparing the results of the high temperature storage test with the conventional one.
A diagram showing the relationship between the composition (y value) of yCu and erasing time,
Figure 6 shows (GeiSbzTei) 52cus as 10
Figure 7 is a diagram showing the change in reflectance when the temperature is raised at °C/min, [(GeTe) x (Sb2Te
,) Diagram showing the relationship between the composition (X value) and crystallization temperature in +-xlsscus in comparison with the conventional one, No. 8
The figure is a diagram showing the results of a high-temperature storage test at a temperature of 80°C for an optical recording medium using (GeSb2Te4) 54Cu@ in comparison with a conventional one.
4) Figure 10 is a diagram showing the relationship between the composition (y value) of l oll-, Co, and erasing time.
) Figure 11 is a diagram showing the change in reflectance when the temperature of 5icOa is raised at 10°C/min.
Fig. 12 is a diagram showing the relationship between the composition (X value) and crystallization temperature in (Ge5bTe*)5scOs in comparison with the conventional one.
Diagram 1 showing the results of a high temperature storage test at a temperature of 80°C for an optical recording medium using sCot in comparison with a conventional one.
Figure 3 is a diagram showing the relationship between the composition (y value) of (Ge2Sb, Te5) +oo-yNiy and erasing time, and Figure 14 is a diagram showing the relationship between the composition (y value) of (Ge2Sb, Te5) +oo-yNiy and erasure time, and Figure 14 is a diagram showing the relationship between the composition (y value) of (Ge2Sb, Te5) + oo-yNiy and erasure time. A diagram showing changes in reflectance, FIG. 15, shows [(GeTe)
x (SbaTes) +-x]@@H7s Figure 16 is a diagram showing the relationship between the composition (X value) and crystallization temperature in comparison with the conventional one, (GeSb2Te4) 5
Diagram 1 showing the results of a high-temperature storage test at a temperature of 80°C for an optical recording medium using aNi* compared with a conventional one.
Fig. 7 is a triangular diagram of Ge-8b-Te showing the Cu-added composition region of the optical recording medium of this invention, and Fig. 18 is A of the triangular diagram.
A diagram showing the composition dependence of the crystallization temperature when Cu is added to Ge5bTe on the B composition line.
A diagram showing the composition dependence of crystallization temperature when Cu is added to e5bTe on the DM line, Figure 20 is A of the triangular diagram.
A diagram showing the composition dependence of erasing time when Cu is added to Ge5bTe on the B composition line. Figure 21 is a triangular diagram CD
A diagram showing the composition dependence of erasing time when Cu is added to Ge5bTe on the composition line. Y value: 00 50 00 Temperature ("C) Xth value nu (GeTe) Section (Sb2Tes) 4 Figure (Sb2Te3) X value 11th (GeTe) Time (h) 12 Figure (SbzTes) Ward 0

Claims (1)

[Claims] 1) In an optical recording medium in which a recording layer on a substrate is irradiated with light and information is recorded, reproduced, and erased by changes in the light, Z is changed to A.
u, Cu, Co or Ni, the general formula [(Ge
Te)_x(Sb_2Te_3)_1_-_x]_1_
An optical recording medium comprising a recording layer having a composition represented by 0_0_-_y[Z]_y (1). (In formula (1), x represents the molar magnification and y represents the mol%.)2)
2. The optical recording medium according to claim 1, wherein Z is Cu and y satisfies the following formula: 0<y≦20 (2). 3) In optical recording media in which the recording layer on the substrate is irradiated with light and information is recorded, reproduced, and erased by the changes in the light, Ge(
When the composition of a) Te (b) Sb (c) is expressed in triangular coordinates, point A (Ge_4_1Sb_9Te_5_0), point B
(Ge_9Sb_3_6Te_5_3), point C (Ge_
6Sb_3_0Te_6_4), point D(Ge_4_0S
b_6Te_5_4), and when W (mol%) satisfies the following formula 0<w≦20...(3), the general formula [Ge(a)Te(b)Sb(
c)]_1_0_0_-_W[Cu]_W An optical recording medium characterized by comprising a recording layer having a composition represented by: