CdHgTe heterostructures on large-area Si(310) substrates for infrared photodetector arrays of the short-wavelength spectral range

Heteroepitaxial structures n-Cd _x Hg_{1 ? x} Te for the near-infrared spectral range (x ≈ 0.4) are grown by molecular beam epitaxy on Si(310) substrates 72.6 and 100 mm in diameter. High composition homogeneity over the structure area is attained; the variation in x for 100-mm wafers is 0.015–0.025. During growth, the mercury-cadmium telluride (MCT) layers are doped with In with the concentration (0.5–3) × 10¹⁵ cm^?3. The magnetic-field dependences of the Hall effect are studied in the range of magnetic fields 0.05–1.0 T at liquid-nitrogen and room temperatures. The experimental values of the electron mobility at room temperature are close to the calculated ones, while at liquid-nitrogen temperature, they are lower than the calculated mobilities. The possible causes of this phenomenon such as the influence of the MCT transition layer at the interface with the CdTe buffer layer and lattice defects of MCT are discussed. The variation in the concentration and mobility of charge carriers in MCT structures after activation annealing are studied.     

HgCdTe structures for dual-band photodetectors operating in the 3–5 and 8–12 µm spectral ranges

A bilayer cadmium-mercury-tellurium (CMT) heterostructure was designed consisting of photosensitive layers of compositions x _CdTe = 0.29–0.32 and x _CdTe = 0.220–0.230, sensitive in the spectral ranges of 3–5 and 8–12 µm, a barrier layer between them, and wide-band variable-gap layers on the heterojunction and the surface grown on a GaAs substrate with ZnTe and CdTe buffer layers. The molecular beam epitaxial (MBE) growth of the heteroepitaxial structure (HES) was controlled by real time ellipsometry. After the growth, the composition distribution throughout the thickness was measured by reflection spectra with layer-by-layer chemical etching. There is good agreement between the results of composition measurements using ellipsometry and reflection spectra. P-type conductivity of bilayer MBE CMT HESs was obtained after thermal annealing at 220–240 °C in an inert gas (helium) for 24 h. The concentration of holes in the photosensitive layers is (4–10) ·10¹⁵ cm^?3 and (8–20) · 10¹⁵ cm^?3 at 78 K.     

Optical monitoring of technological parameters during molecular-beam epitaxy

It is shown that one can use low-coherence tandem interferometry to measure the substrate temperature during the course of molecular-beam epitaxy in the case of oblique incidence of the probing light onto the surface. The temperature conditions in the Ob??-M installation for growing heteroepitaxial structures of cadmium and mercury tellurides and in the RIBER SIVA-21 installation for the growth of silicon-germanium structures are investigated. Calibration curves relating the readings of the standard thermocouple fixed within the heater to the true substrate temperature in the range 0?C500°C are created.     

An Optical Study of Disordering in Cadmium Mercury Telluride Solid Solutions

Technical Physics Letters - The disordering in cadmium mercury telluride solid solution films grown by molecular beam epitaxy on Si and GaAs substrates has been examined by optical transmission and...     

HgCdTe-Based 640 × 512 Matrix Midwave Infrared Photodetector

Journal of Communications Technology and Electronics - Matrix photosensitive elements based on a HgCdTe semiconductor solid solution on silicon substrates with 640 × 512 elements at a pitch of...     

Optical and Structural Properties of HgCdTe Solid Solutions with a High CdTe Content

Semiconductors - The results of studying the optical transmission, photoconductivity, photoluminescence, and X-ray diffraction of HgCdTe solid-solution samples with a high content of CdTe (molar...     

Photodetectors with 384 × 288 Matrix Elements for the Infrared Range of 8–10 Microns

Journal of Communications Technology and Electronics - Abstract—Design and fabrication of photosensitive array elements in the 384 × 288 element format with a step of 25 μm with a...     

A Megapixel Matrix Photodetector of the Middle Infrared Range

Journal of Communications Technology and Electronics - Abstract—The characteristics of MWIRs focal plane aeeays made in the form of a hybrid chip based on a planar n+–p-HgCdTe focal...     

Methodological and instrumental problems in high-precision in situ ellipsometry diagnostics of the mercury cadmium telluride layer composition in molecular beam epitaxy

Problems of high-precision in situ ellipsometry diagnostics of the composition of a mercury cadmium telluride (MCT) solid solution in the process of its growth using the molecular beam epitaxy are considered. The required precision was estimated for ellipsometry measurements aimed at determining the MCT composition with a permissible dispersion of ±0.003 mole fraction of CdTe. It has been revealed that for ellipsometers based on the static photometric scheme the instability of measurements is mainly caused by a random change in the directivity of the laser radiation. In combination with polarization nonuniformity over the area of the optical-section elements, this results in continuous drift of measured ellipsometric parameters. Based on these investigations, a high-stability laser ellipsometer has been designed. When used to monitor the in situ MCT layer growth by the molecular beam epitaxy, it allowed a decrease in the dispersion of the MCT composition by an order of magnitude from experiment to experiment and its precision to be maintained at a level of ±0.003 mole fractions of CdTe.     

Effect of post-implantation annealing on the current-voltage characteristics of IR photodiodes based on <Emphasis Type="Italic">p</Emphasis>-HgCdTe

Current-voltage characteristics of IR photodiodes and distributions of charge carriers in n ⁺-n ⁻-p-structures based on vacancy p-doped Hg_{1 − x} Cd _x Te films with x = 0.22 are examined. Three-dimensional numerical modeling of the distribution of charge carriers and current-voltage characteristics during photodiode annealing is performed. The calculations predict that large tunnel currents in diodes after implantation can result from an elevated (more than 10¹⁵ cm⁻³) concentration of donors in the n ⁻-layer, which enhances tunneling by decreasing the thickness of the space charged region of the n-p-junction, and also from a small (less than 3 μm) depth of the p-n-junction.