IE34899B1 - Improvements in or relating to semiconductor devices - Google Patents

Abstract

1340617 Electroluminescence WESTERN ELECTRIC CO Inc 19 April 1971 [16 Feb 1970] 21830/71 Heading C4S [Also in Division H1] A semi-conductor device comprises a semiconductive, electroluminescent, charge carrier storage medium, a means for storing the carriers at a first site in the medium, and a means for transferring the carriers to a second site, a radiative output being obtainable on the recombination of the carriers with the bulk carriers of the medium. Electrode and insulator materials and thicknesses are given. The principle of operation is shown in the shift register of Fig. 2 wherein a series of electrodes 22a, 23a &c. overlie the medium 20 on an insulating layer 21. Carriers at the input 25 migrate to the depletion region 27a under electrode 22a, formed by suitable biasing, and is thereafter sequentially transferred to depletion regions sequentially formed under the next electrode by suitably timed voltage pulses on 22<SP>1</SP>, 23<SP>1</SP> and 24<SP>1</SP>. The carriers may alternatively be generated not only at the input, but along the entire device, by light or other ionizing radiation incident upon the medium, movement of the charges towards the output (by means of suitable voltage pulses to the electrodes), resulting in a video signal corresponding to the image on the medium. Alternatively a video signal may produce an image if the video signal is fed into the device, and when all the sites have been charged, or not, by the signal, a bias on the electrodes may cause the carriers to recombine forming an image in the electroluminescent medium. Fig. 10 is such a device, in which in a medium of N type GaAs P type regions 117a, 118a &c. are formed. The electrodes 115a, 116a &c. form the gate electrodes, effectively, of a series of IGFETS, the drain of one FET forming the source of the next. By applying alternating clock pulses to the electrodes, charge carriers can be caused to travel from site to site sequentially, the channels being opened and closed sequentially. When the final site is reached, all the carriers may be forced to recombine simultaneously with the bulk carriers of the medium producing an image in the medium. This image may be applied to a photo-cathode of a CRT to form an image on the screen. Figs. 5A-5C (not shown) illustrate various output devices. Specifications 1,340618 and 1,340,619 are referred to. [GB1340617A]