HgTe-based photodetectors in Poland

Abstract

The purpose of this paper is to review the main achievements in the investigations of HgTe-based ternary alloys and point out the Polish contributions in development of the middle and long wavelength infrared photodetectors. Research and development efforts in Poland were concentrated mostly on uncooled market niche.At the beginning, a modified isothermal vapor phase epitaxy has been used for research and commercial fabrication of photoconductive, photoelectromagnetic, and other HgCdTe devices. Bulk growth and liquid phase epitaxy were also used. Recently, the fabrication of infrared devices relies on low temperature epitaxial technique, namely metalorganic vapor phase deposition.At present stage of development, the photoconductive and photoelectromagnetic (PEM) detectors are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, photodiodes offer high performance and very fast response. However, conventional photovoltaic uncooled detectors suffer from low quantum efficiency and very low junction resistance. The problems have been solved with advanced band gap engineered architecture, multiple cell heterojunction devices connected in series, and monolithic integration of the detectors with microoptics.In final part of the paper, the Polish achievements in technology and performance of HgMnTe and HgZnTe photodetectors are presented.