Claims
- 1. A method of making a glass-sealed transmission mode gallium arsenide photocathode comprising the steps of:
- (a) preparing a germanium seed crystal for epitaxial growth;
- (b) epitaxially growing a p-doped gallium arsenide photoemitting layer onto the prepared germanium crystal using the metal alkyl-hydride vapor-phase process;
- (c) epitaxially growing a p-doped gallium aluminum arsenide passivating layer onto said photoemitting layer using the metal alkyl-hydride vapor-phase process;
- (d) depositing a suitable antireflection or interface layer onto said passivating layer;
- (e) fusion bonding the antireflection or interface layer surface of the structure composed of seed crystal, photoemitting layer, passivating layer, and antireflection or interface layer to a glass faceplate that serves as the input window of the device;
- (f) preferentially etching away the exposed germanium seed crystal to expose the photoemitting layer;
- (g) applying ohmic contact to the periphery of said photoemitting layer for effecting electrical contact to the photocathode;
- (h) applying a suitable glass/air antireflection coating on the exposed photon input side of the glass window; and
- (i) activating the photoemitting layer by heat cleaning in vacuum and applying monolayer amounts of cesium and oxygen to the photoemitting layer.
- 2. The method of claim 1 wherein the composition of the gallium arsenide photoemitting layer is modified by the incorporation of indium to form gallium indium arsenide.
Government Interests
The invention described herein may be manufactured, used, and licensed by the U.S. Government for governmental purposes without the payment of any royalties thereon.
US Referenced Citations (4)
Non-Patent Literature Citations (1)
Entry |
G. A. Antypas et al. "Glass-Sealed GaAs-AlGaAs Transmission Photo-Cathode Appl. Phys. Lett., vol. 26, pp. 371-372 (1975). |