Accession Number : AD0914943

Title :   Broadband Near Infrared Laser Detector.

Descriptive Note : Final rept.,

Corporate Author : VARIAN ASSOCIATES INC PALO ALTO CA

Personal Author(s) : James, Lawrence W.

Report Date : OCT 1973

Pagination or Media Count : 120

Abstract : The near-bandgap photoemission from III-V photocathodes with a bandgap less than the heterojunction barrier was shown to be due to thermally-assisted emission over the barrier rather than tunneling through it. The effects of a reduction in escape probability with stress in the active layer have been shown to be very important in the performance of transmission mode photocathodes, making thermal expansion matching considerations important. The problems involved in making ideal glass-sealed transmission photocathodes, including strain and Zn outdiffusion, are discussed and recently-improved performance is demonstrated. The necessity for treating four element-grown heterojunctions as graded quaternaries is demonstrated and applied to transmission photocathodes. Record-setting quantum efficiencies are demonstrated from a quaternary active layer. Use of quaternaries introduces an additional degree of freedom, allowing independent choice of the transmission photocathode long and short wavelength cut-offs while maintaining the lattice matching condition.

Descriptors :   *INFRARED LASERS), (*INFRARED DETECTORS, (*PHOTOCATHODES, INFRARED LASERS), BROADBAND, NEAR INFRARED RADIATION, GALLIUM ARSENIDES, GALLIUM PHOSPHIDES, SUBSTRATES, DOPING, ZINC, VAPOR PHASES, LIQUID PHASES, RECOMBINATION REACTIONS, SEMICONDUCTORS, EPITAXIAL GROWTH, ALUMINUM, INDIUM, DIFFUSION, THICKNESS.

Subject Categories : Electrical and Electronic Equipment
      Lasers and Masers
      Infrared Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE