Optoelectronic Electron Emitter

The report describes research performed during a two-year period in order to develop a semiconductor cold-cathode electron emitter with emission properties suitable for practical applications. Greatly improved cold-cathode structures based on negative electron affinity surfaces and on GaAs-(AlGa)As heterojunction structures grown by liquid phase epitaxy were developed. The key to the successful development of this device was the ability to obtain highly doped p-type GaAs with electron-diffusion lengths as high as about 5 to 7 micrometers and a technique for the confinement of the carrier flow to the desired emitting area. Extensive studies on dc operation and cathode life were conducted under continuously pumped vacuum conditions as well as in sealed tubes, and operation was obtained for a period of 360 hr.
See also Semi-annual rept. no. 3, AD750611.