Accession Number : ADA198101

Title :   Hg,CdTe Material Optimization for Carrier Lifetime Maximization.

Descriptive Note : Final technical rept. 1 Sep 86-30 Apr 88,

Corporate Author : AEROJET ELECTROSYSTEMS CO AZUSA CA

Personal Author(s) : Vydyanath, Honnavalli R.

Report Date : 14 JUL 1988

Pagination or Media Count : 71

Abstract : Hg(1-x)Cd(x)Te is a variable bandgap allow semiconductor which has recently emerged to perhaps the single most important infrared detector material with extensive military and civilian applications. The minority carrier lifetime in p-type base material for n(+)p photodiode structures is normally much below the radiative limit and is limited by the presence of Shockley-Read Centers which are related to the presence of impurities and native defects in the material. In order to obtain photo diode performance close to the theoretical limits, it is essential to prepare mercury cadmium telluride material with carrier lifetime approaching radiative limit. This is possible only when the origin of the Shockley-Read Centers limiting the carrier lifetime is established and the material preparation conditions are optimized so that the concentration of these centers is reduced to a minimum. The goal of the program was to optimize the preparation conditions of the (Hg,Cd)Te material such that the carrier lifetime was maximized. Both undoped and doped crystals were investigated. To begin with, indium as an n-type dopant was investigated. At the end of the duration of the program, the material had been optimized so that the p-type carrier concentration can be controllably reproduced via anneals under well defined thermodynamic conditions, namely temperature and partial pressure of Hg., the behavior of indium doped (Hg,Cd) Te was well established. Carrier lifetime measurements were carried out in epitaxial HgCdTe films. (aw)

Descriptors :   *CADMIUM TELLURIDES, *MERCURY COMPOUNDS, *SEMICONDUCTORS, CHARGE CARRIERS, DOPING, CRYSTALS, DEFECTS(MATERIALS), IMPURITIES, INDIUM, INFRARED DETECTORS, LIMITATIONS, MATERIALS, MEASUREMENT, MILITARY APPLICATIONS, P TYPE SEMICONDUCTORS, PHOTODIODES, PREPARATION, RADIATION, THERMODYNAMICS, N TYPE SEMICONDUCTORS, SEMICONDUCTING FILMS.

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE