DE1960370C - Electronic solid-state switching element - Google Patents

Description

_also from the "Zeitschrift für Angewandte Physik", Rd 28 1969, no. 3, pp. 143 to 148, known. ^Bd The 'switching effect in the glass semiconductors the charge carriers between the energy and the conduction band, after O ν shi η sky on a "gap" in the Move-SchkeH based, as in the article "Simple Volume Model for Amorphous Semiconducting Alloys" in " Physical Review Letters, May 1969, pp. 1065-1068. In this energy range the electrons are almost immobile. The load carriers are therefore easily received. Once the energy states between the Kngsband and the Fermi level are filled on the element in the state _to niederohm.gen because the additionally injected electrons, is sawn in the energy state above the Beweghchke.tslucke

«-KIÄSIS because of that too

The following ^ gJ
hike and increase the ^k

Standing .S ^6/1 * ™ ^ J body-switching elements

star ^ann ^ ™ ^ £
parallel to the

body can · ™ same material

15th By adding a small amount of semiconductor surface to such semiconductor layers, the potential is increased _{by the} addition of a

ind.

such a semiconductor _{body ffkt} . It is therefore essential for the semi-essential

^ _s ^ _hcrsteim r is, and it .st SuSücnnrtewd sufficient. Suppuration of the invention d.enen d, e

Ass r lI ^ kä

are subject to, as shown in Fig. 2 schemat.sch is illustrated. There the energy E is the charge tiger in a sectional plane of the semiconductor body m depending on its distance χ from one of the electrodes of the semiconductor body applied * band E _v and conduction band E _c have different SLn over the extent of the semiconductor body. The Fermi level is marked Er . In the high-resistance area, the energy state between the maximum energy E ₁ and the Ferm, level Ep can first be filled. The range of motion is low here.

he mr _{ktfode of a} switching

° Invention in a diagram

a ₅ becomes des

3 » has a it

Charge Areans move freely. "

S ¹ S ÄiÄ

“SS. W the already one

zium3 and nl

Jnrtt. preferably by the _as- shaped connection of the S ^ hübewndeie Germa- ^ ₀ RH ₁ GeCl ₄ and SiIif _t hydrogen H ₁ SiCl, silicon distance as germanium, and potential threshold of the applied

Tunnel-

. The known switch emenu with.

Forms valleys and cannot distribute them over the entire area. The result is an excessive _br: heating of the semiconductor body in '. ^ ^0. ^^ "greater powers, leading to the melting of the thin

"CeI ⁰ K iS! Gt ^{e n} dahTr the object of di Γ carrying capacity of the known switching elements for

wmmm _{£> eo the} dielectric constant _χ ^ _Boltzmann constant _T the absolute temperature elementary charge and “ _{D the} donor density

1Ig

3SMS Sl = SSMS

3S

to protect finished semiconductor bodies against mechanical damage or leakage currents. For this purpose, the switching element can, for example, be arranged in a housing or enclosed by a self-hardening plastic. The semiconductor body can contain, for example, about 100 layers of different bandwidth, the thickness d of which can be, for example, about 1 μ in each case. The length of the entire semiconductor body will therefore generally not significantly exceed 100 μ.

The width d and the number of silicon layers 3 determine the switching voltage I / »of the switching element. Its switching current 1 is given by the mobility of the charge carriers and by the distance o between the conduction band edges of silicon and germanium. If the ratio of the forbidden bands E ^ \ E _at and thus generally also the energy difference O _{1 is} too great, the silicon layer 3 can also be replaced by a silicon-germanium alloy. With such a gapless mixed crystal row, the band gap of which in FIG. 5 is illustrated schematically, the required switching current can be changed continuously and thus a desired sound current I _s can also be set. There the width of the forbidden zone /! A dependence on the mixing ratio of the alloys silicon and germanium is plotted in a diagram. The width of the forbidden Zone AE is 1.1 eV for pure silicon and 0.6 eV for pure germanium. In a silicon-germanium mixed crystal with z. B. 80% germanium and 20% silicon, the width AE is higher by a value, which is shown in the figure with a distance α , and the band gap according to FIG. 5 increased by the proportions O ₁ and a ₂ , since a = α, + O _x applies. In the case of n-conducting semiconductor material, the distance α determines the magnitude of the switching current / ».

The semiconductor bodies can consist of semiconductor elements or compounds of the elements of III. and V. as well as II. and VI. Group of the Periodic Table. Semiconductors with a high carrier mobility of about μ> 100 cm ² / Vsec and which form mixed crystals are particularly suitable. Gallium arsenide GaAs and gallium phosphide GaP, for example, have these properties. In n-type mixed crystals, the mobility of the electrons is generally greater than the mobility of the defect electrons. With a gapless mixed crystal row according to FIG. 5, the level of the potential threshold can be continuously adjusted with the proportion of the two materials, because the switching current / "is determined by the level of the potential threshold in the conduction band.

In addition to gallium arsenide and gallium phosphide, there are also other semiconductor compounds, the mixed crystals form, for example, indium arsenide InAs and indium phosphide InP, suitable

The individual layers can preferably be produced by the known epitaxy or also by vapor deposition be applied to the semiconductor body in a vacuum. Also the spraying on of the semiconductor material containing solvent is possible.

S In addition, sputtering, especially cathode sputtering, is also used to apply the individual Semiconductor layers suitable.

Silicon and germanium can preferably be separated from a gaseous halogen

xo compound, in particular through high temperature reduction of germanium or silicon tetrachloride with hydrogen as carrier gas:

SiCl ₄ + 2H ₂ -Si + 4HCi

be won.

For this purpose, a gas stream containing the semiconductor material can alternate via the Semiconductor bodies are conducted. Under certain circumstances, it can be useful to flow the gas with the gaseous semiconductor compound, for example the gaseous germanium compound, intermittently one feed gaseous silicon compound. Then alternate a layer of germanium

as and as a further layer a germanium-silicon compound deposited.

The A ^m B ^v compounds supplement the elements germanium and silicon with semiconductor materials with similar properties, the forbidden zones being essentially below that of germanium and above that of silicon. Gallium arsenide and gallium phosphide also form a seamless series of mixed crystals. These connections can therefore be used advantageously for the production of switching elements according to the invention. As explained in the embodiment of germanium and silicon compounds may be of such ^1IL A B ^V also alternately one layer, preferably gallium arsenide, GaAs, and a subsequent layer of the same element of the III. Group and another of the V group, preferably gallium phosphide GaP, are applied. Furthermore, the second layer can also contain the material of the first layer and, in addition, a further semiconductor compound which is added to produce the potential waves and which can preferably be fed in bursts to the gas flow of the material of the first layer. In this way, according to the invention, a semiconductor body with alternating layers of gallium arsenide GaAs and gallium arsenide with gallium phosphide GaAsP can be produced.

In the exemplary embodiment, an η-conductive semiconductor body was selected to explain the invention,

SS because in general the mobility of the charge carriers in η-conducting semiconductor materials is greater However, p-type materials are also suitable.

1 sheet of drawings

Claims (10)

Doi.,. T, ntn, ii ^ .. Germanium another semiconductor material from Ger- Fatent claims. manium tetrachloride with hydrogen (HxGeCl4) 1. Electronic solid-state switching element is deposited with and the gas flow temporarily a semiconductor body to which two planar silicon tetrachloride (SiCl ₄ ) is added, ohmic contact electrodes and several layers th of semiconductor material and its —— - resistance decreases significantly as soon as the current exceeds a predetermined value, the invention relates to an electronic characterized in that the solid-state switching element with a semiconductor body, Semiconductor body made of alternating layers of two flat, ohmic contact electrodes (2, 3, 4) consists of the same conductivity type and that and several layers of semiconductor material on- at least one conductive tape (E ₀ and / or E _v ) and whose resistance is significantly reduced. at least one of the layers (2, 3, 4) potential as soon as the current has reached a predetermined value contains thresholds. exceeds. 2. Solid state switching element according to claim 1, 15 It is a contactless electronic switching element characterized in that the layers (2,3,4) are known, the semiconductor body of which is made of monocrystalline made of two materials with different ribbon semiconductor material with five layers alternating width exist. opposite conductivity type exists. If you lay 3. Solid-state switching element according to claim 2, this in the literature according to its inventor as characterized in that the materials 20 "Shockley Diode" designated switching element form a chip mixed crystals. voltage, the current increases roughly proportionally to the 4. Solid-borne sound element according to claim 1, connected voltage up to a predetermined value, characterized in that the layers each th value in which the resistance is reduced by leaps and bounds essentially from a connection of a first and the amperage is also abruptly A ⁱⁿ B ^v connection with a second A ⁱⁿ B ^v -Ver- as increases many times over. Their switching time is about binding that is the same element of III. Group] 0 " ^e sec. of the periodic system as the first A ^nI B ^v -Ver- A connection known as "Diac" and another element of the V group element is preferably used in telecommunications, and that the proportions of the and electronic control technology used. There components of this connection when connected to each other- 30 switches the current in the manner mentioned in the two following layers are different. Directions. The change in the switching status at 5. Solid state switching element according to claim 4, exceeding the switching voltage is in F i g. 1 characterized by the fact that the layers are visible from. It shows the current-voltage characteristics of a connection of gallium phosphide <GaP) with the line of the switching element. Is attached to the electrodes Gallium Arsenide (GaAs) exist. 35 of the switching element applied a voltage, it flows 6. Solid state switching element according to claim 2, a relatively low current which is approximately linearly characterized in that the semiconductor body increases with the applied voltage. As soon as an alternating layer of an A ⁱⁿ -B ^v - predetermined voltage value, the so-called switching connection and a subsequent layer of the voltage U ,, is exceeded, the element connection switches an A ⁱⁿ B ^v connection with an * o in the low-resistance state around this characteristic curve other A ^m B ^v connection, which the same EIe- is known from the literature. ment of the III. Group of the Periodic Table From »Ideas of Exact Knowledge« (Science and and another element of Group V, Technik in der Sowjetunion), 1969, no. 8, pp. 505 to 511, having. is also known that the semiconductor body of construction 7. Solid state switching element according to claim 6, 45 elements with the in F i g. 1 illustrated characteristic characterized in that the semiconductor body line are also made of vitreous semiconductors alternately a layer of gallium can. These semiconductors consist of alloys of the arsenide (GaAs) and a subsequent layer of a sulfide, selenide and telluride and form a compound of gallium arsenide with gallium-rich group of amorphous substances, which in phosphide (GaAsP). 50 their physicochemical properties dem 8. Processes for making a semiconductor glass are similar. They differ from the bodies for a solid-state switching element according to known oxide glasses only in their coloration, claim 1 or 3, characterized in that their electrical conductivity is purely electronic on a semiconductor body of a compound type and independent of the content of admixtures of two elements of the IV. Group or a 35 It has been shown that thin slices of such A ^m B ^v compound alternately the same glass semiconductor also have the aforementioned switching compound with different proportions of the effect, which, however, when individual elements are exceeded from a gaseous Connection of a predetermined flow value, the switching current manure is applied. according to FIG. 1, is triggered. In contrast to the 9. A method for producing a semiconductor 60 known switching elements with a monocrystalline half-body for a solid-state switching element after conductor body contain this amorphous glass semiconductor-claim 1 or one of claims 2 and 3, body no layers with alternating opposite characterized in that on a semiconductor-like conductivity type. You have opposite the body from an element of the IV. group each known switching elements the advantage of a substantially alternating another element of the IV. group 6s lent shorter switching time, which is about 10 "· see, is deposited from the gas phase. Electronic solid-state switching elements of this type, 10. The method according to claim 9, characterized in that their semiconductor bodies are made from elements of III., IV. indicates that on a semiconductor body consists of and V. group of the periodic system are