Igor S. Virt

Peculiarities of MCT ion etching in rf mercury glow discharge

Results of complex investigations of n- and p-type Hg1-xCdxTe (MCT) etching in RF mercury glow discharge have been presented. Discharge was induced in quasi-closed volume. Results of technology parameter influence onto velocity of etching have been presented. It has been shown that MCT treatment by mercury ions can be carried out with etching velocity up to 30 micrometers /hour. Surface heating under these conditions slightly increases the temperature (up to 50 degree(s)C) and stoichiometry deviations are absent. It has been found that the width of disturbed layer depends on bias voltage and is smaller than 2.5 micrometers . Electrophysical parameters of n- and p-type MCT after processing have been studied. Etching of n-MCT forms the n+-n structure. The width of n+-layer corresponds to the width of disturbed zone. In the case of p-MCT, there exists inversion of conductivity type at depths exceeding those corresponding to the case of argon ions etching. It is supposed that high inversion velocity is caused by saturation of MCT surface by mercury ions during treatment.

MnHgTe epitaxial layers grown by rf sputtering in mercury glow discharge

The structure of MnxHg1-xTe thin layers with x equals 0.12 - 0.19 deposited on CdTe substrates with (111) and (110) orientations has been investigated. The glow radio-frequency (RF) (f equals 13.56 MHz) discharge was excited according to the diode scheme in magnetic field. The process was carried out under Hg vapor pressure from 5 (DOT) 10-3 to 8 (DOT) 10-3 Torr with quasiclosed volume. The possibility of Hg vapor pressure regulation allowed to carry out reactive process of MnHgTe layers condensation. It has been shown, that RF sputtering of MnHgTe in mercury glow discharge permits to obtain epitaxial layers with perfect structure. Optimal values of substrate temperatures which lead to epitaxial growth are from 230 to 250 degrees Celsius. The carrier concentrations and their mobilities have been determined.

Controling the properties of bulk Hg1-xCdxTe by laser-induced shock waves

The possibility of defect structure and consequently basic parameters (carrier density, their mobility and lifetimes) control in bulk mercury-cadmium telluride (MCT) using the nanosecond laser irradiation induced shock waves (LSW) is investigated. MCT bulk samples (with composition x equals 0.2) both n- and p- type with different initial structural quality were treated. The post-treatment changes have been detected by galvanomagnetic and photoelectric (lifetime) techniques. Two depending of irradiation mode mechanisms of interaction between LSW and bulk Hg1-XCdXTe defect subsystem are given. The potentiality of this technique as a technological tool for controlled modification of MCT parameters is discussed.

Electrical properties of CdTe:Cl single crystals grown by sublimation technique

The current-voltage characteristics are investigated in single crystals of CdTe doped with Cl. Measured samples were n -type conductivity with resistivity ρ=(0.5-2.0)x108 Ohmxcm, electron concentration n =(0.5 ÷ 2.0)x108 cm-3 and electron mobility μ = 280 ÷ 300 cm2/Vxs. Experimental data are explained in the framework of theory of highly doped and highly compensated semiconductors. The mobility-lifetime product measured at room temperature is found to be in the order of (1÷5)x10-4 cm2xV-1. It means that this material can be used for manufacture of X-ray detectors.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Composition and Electrical Properties of Hg x Cd1 – xS Whiskers

Data are presented on the morphology, composition, and electrical and photoelectric properties of HgxCd1 – x S (x = 0.25–0.6) whiskers.

Photoprocesses in A2B6 whiskers

CdTe needle-like crystals were grown by CTR method in CdTe-Br system. Their resistivity is changed from 10 to 1000 (Omega) (DOT)cm depending on crystal diameter: it increases with the increase of wire diameters from 50 to 250 micrometer. Specimens with (rho) > 10 (Omega) (DOT)cm are observed to be photosensitive at 300 K. Photoconductivity spectrum is shown to depend on the whisker diameters. A model explaining the whisker electronic and photoelectrical parameters and their dimensional dependencies is discussed. This model is based on account of the surface states.

Photoprocesses in A 2 B 6 whiskers

CdTe needle-like crystals were grown by CTR method in CdTe-Br system. Their resistivity is changed from 10 to 1000 (Omega) (DOT)cm depending on crystal diameter: it increases with the increase of wire diameters from 50 to 250 micrometer. Specimens with (rho) > 10 (Omega) (DOT)cm are observed to be photosensitive at 300 K. Photoconductivity spectrum is shown to depend on the whisker diameters. A model explaining the whisker electronic and photoelectrical parameters and their dimensional dependencies is discussed. This model is based on account of the surface states.

Laser epitaxy of HgCdTe ternary alloy

In the paper, an analysis of experimental conditions of pulsed laser deposition (PLD) of AIIBVI ternary alloy layers is presented. The growth conditions and photoelectric parameters of the layers have been measured. Two lasers were used for the ablation: YAG:Nd3+ and excimer XaCl. Photo-electrical properties of HgCdTe layers have been measured in the spectral range of 4-11 micrometers . Electro-physical properties confirmed the high carrier mobilities and low electron concentrations. Crystallographic quality of the layers has been varied depending on the kind of substrate. Their structure changes from amorphous via polycrystalline to the oriented mosaic. The PLD method allows easily obtaining periodic structures of varying layers composition with period d<10A.

Growth and some properties of tellurium compound whiskers

CdTe, CdXHg1-XTe (x equals 0.1), and PbTe whiskers were grown by chemical transport reaction (CTR) method in closed system. An investigation of growth kinetics and morphology of the whiskers shows that they grow according to both vapor-liquid-solid (VLS) and vapor-crystal (VC) mechanisms. The dependencies of resistivity and photoconductivity on the whisker diameter were found and discussed. Some structure imperfections in the whiskers of large diameters (d > 100 micrometer) are assumed to be present.