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It is shown that when using a standard electrochemical profiling recipe that applies intensive illumination by halogen lamp with power up to 250 W of n+/n GaAs structure to generate the holes necessary for etching, the resulting electron distribution profile differs from that set during growth for an electron concentration in the n+-layer > 4 × 1018 cm–3 when using EDTA electrolyte. This difference is due to the appearance and development of etching pits caused by the increase in the degree of defectivity of GaAs layers with increasing concentration of the donor impurity—silicon. To obtain adequate electron distribution profiles in n+/n GaAs structures it is necessary to limit the illumination up to 25 W. [ABSTRACT FROM AUTHOR]

The polarity type, surface morphology, electrical properties, and deep trap spectra were studied for undoped AlxGa1-xN films (x=0–0.6) grown by molecular beam epitaxy on on-axis (0001) sapphire using composite buffers consisting of low temperature (LT) AlN nucleation layer, AlN, and AlN/AlGaN superlattice. It is shown that the films grow with N-polarity if the LT AlN layer is deposited under N-rich conditions and with Ga-polarity for the LT AlN layers deposited under Al-rich conditions. For both polarities the film morphology was acceptable for fabrication of typical GaN-based devices. It is demonstrated that the Ga-polar AlGaN films are heavily compensated p-type, with the dominant acceptors believed to be due to C. N-polar films are n type, with the residual donors pinning the Fermi level being most likely due to Si. N-polar films show a high concentration of deep electron traps. [ABSTRACT FROM AUTHOR]

The variable-field Hall data of p-MCT films were filtered by weighting low-pass digital filter with Blackman win-dow before mobility spectrum analysis. The used cutoff frequencies lay in range 0.1-0.7 Hz. It was obtained that the digital filtration allows determining of minor elec-tron's mobility at low temperatures (77-90 K). The electron mobility values, obtained by mobility spectrum analysis in conjunction with multicarrier fitting well agreed with result of photoconductivity in magnetic field for Faradays geometry.(© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The possibility of using AlN/Al 2O 3 substrates to grow AlGaN/GaN hetero-epitaxial structures with a two-dimensional electron gas is studied. A method of calibrating the temperature of the substrates by measuring the thermal radiation spectrum is proposed. Differences between AlN/Al 2O 3 substrates that lead to differences in the electrophysical parameters of the grown structures are determined. AlN/Al 2O 3 substrates were used to grow AlGaN/GaN samples with a two-dimensional electron gas mobility in excess of 1300 cm 2/(V · s) at an electron concentration in the channel higher than 10 13 cm −2. [ABSTRACT FROM AUTHOR]

The Al x Ga1- xN layers with a wide range of AlN molar fraction (0 < x < 0.6) were grown by ammonia MBE on (0001)-oriented sapphire substrates using silane as the silicon dopant. The structural, electrical and optical properties of the layers were investigated by atomic force microscopy, X-ray diffraction, Hall, Raman, photoluminescence and cathodoluminescence measurements. It was found that doping affects surface morphology, dislocation density and luminescence intensity of the Al x Ga1- xN layers. A sharp decrease of the luminescence intensity for the heavily doped GaN and Al0.3Ga0.7N layers was explained by enhancement of the nonradiative recombination rate in degenerate GaN layers and by an increase in the defect concentration in AlGaN layers. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The effect of an external magnetic field on the dark current of photodiodes in far-IR matrix photodetector arrays fabricated by boron ion implantation into heteroepitaxial cadmium mercury telluride (CMT) layers has been studied. A new method is proposed for separately determining the lateral and normal dark current components in CMT photodiodes of the matrix photodetectors. It is established that the dark current of these photodiodes (at 77 K) with dimensions comparable with the minority carrier diffusion length is determined primarily by the lateral component. [ABSTRACT FROM AUTHOR]