Influence of TDMAAs Acceptor Precursor on Performance Improvement of HgCdTe Photodiodes

Abstract

One of the key factor which determine HgCdTe photodiode quality is acceptor doping efficiency. This paper presents significant progress made over the past three years in development of acceptor doping technology in metalorganic chemical vapour deposition HgCdTe photovoltaic detectors. High acceptor doping is required for P + -contact layers, whereas low doping is necessary for p-type absorbing base layer. Previously, AsH3 precursor was used as an acceptor dopant. This precursor is partially incorporated as electrically neutral As-H pairs, which are likely to be recombination centres in HgCdTe and in consequence influence on the carriers lifetime lowering. Substituting of AsH3 by TDMAAs resulted in higher carrier lifetimes and thereby about one order of magnitude higher R0A product of HgCdTe photodiodes in temperatures close to 230 K.

MOCVD Grown HgCdTe Heterostructures

“…Indispensable in understanding the electrical properties of doped layers is the ability in interpretation of undoped layers results. The electrical properties of undoped MOCVD-grown MCT are dependent on the different parameters such as contamination from alkyls or substrates [3,12], crystallographic defects such as microtwins on (111) orientation, quench cooling conditions and native defects like mercury vacancies and others [13]. Although such defects do not affect interpretation of highly doped layers like contact layers, they may confuse interpretation of low-doped layers like absorbing layers in photodiodes structure.…”