<title>HgCdTe epilayers on GaAs: growth and devices</title>

View of basic and specific physical and chemical features of growth and defect formation in mercury cadmium telluride (MCT) heterostructures (HS's) on GaAs substrates by molecular beam epitaxy (MBE) was made. On the basis of this knowledge a new generation of ultra high vacuum set, ultra-fast ellipsometer of high accuracy and automatic system for control of technological processes was produced for reproducibility of MCT Hs's growth on substrates up to 4" in diameter. The development of industrially oriented technolgoy of MCT HS's growth by MBE on GaAs substrates 2" in diameter and without intentional doping is presented. The electrical characteristics of n-type and p-type of MCT HS's and uniformity of MCT composition over the surface area are excellent. The residual donor and acceptor centres are supposed as hypothetically tellurium atoms in metallic sublattice ("antisite" tellurium) and double-ionised mercury vacancies. The technology of fabricating focal plane arrays is developed. The high quality characteristics of infrared detectors conductance and diode mode are measured. Calculations of detector parameters predicted the improvement in serial resistance and detectivity of infrared diode detectors based on MCT heterostructures with graded composition throughout the thickness.