Electrical characteristics of Hg/sub 1-x/Cd/sub x/Te epilayers subjected to ultrasonic influence
The degradation of electrophysical characteristics of Hg1-xCdxTe thin films grown by LPE and MBE as a consequence of the high-frequency and high-intensity elastic deformation effect was investigated It was determined that parameters of Hg1-xCdxTe thin films grown by MBE are stable to ultrasonic influence whereas for Hg1-xCdxTe thin films grown by LPE the mobility decrease and the change of the conductivity type at low magnetic field wae observed The best agreement between experiment and calculation was obtained in the frame of assumption about forming of the thin layer with opposite conductivity. The possible mechanism of Ihe observing effects was analyzed.
New generation of infrared photodetectors
HgCdTe remains the most important material for infrared photodetectors despite numerous attempts to replace it with alternative materials such as closely related mercury alloys (HgZnTe, HgMnTe), Schottky barriers on silicon, SiGe heterojunctions, AlGaAs multiple quantum wells, GaInSb strain-layer superlattices, high-temperature superconductors and especially two types of thermal detectors: pyroelectric detectors and silicon bolometers. It is interesting, however, that none of these competitors can compete in terms of fundamental properties. In addition, HgCdTe exhibits nearly constant lattice parameters, which is of extreme importance for new devices based on complex heterostructures. Examples of novel devices based on three-dimensional heterostructures are presented.
Extension of longwavelength IR photovoltaic detector operation to near room-temperatures
Abstract Practical realization of near room temperature (230–300 K) longwavelength (5–12 μm) photovoltaic detectors is reported. The devices are epitaxial n+ip p photodiodes operated at ambient temperature or with a simple, two-stage thermoelectric cooling. The performance of the photodiodes has been improved by the use optimized composition and doping profile structures. The tunnel currents were minimized by interfacing the n+ and p-type layers with a thin (0.5 μm) lightly doped i-region. The quantum efficiency has been increased by the use of backside reflector. Further improvement of performance was achieved by the use of monolithic optical immersion. Large area devices with useful performance were obtained by the use of small close-spaced elements connected in series. The near room temperature photovoltaic detectors are of particular significance for very low and very high frequency applications.