Madhukar Gautam

Growth and characterisation of Hg1 − xCdxTe (0.21 < x < 0.36) epilayers grown from Te-rich solution by the dipping technique

Hg1 − xCdxTe (0.21 < x < 0.36) epilayers were grown on 〈111〉 CdTe substrates by liquid phase epitaxy from a supersaturated Te-rich solution by the dipping technique at 440 and 470°C. Mercury vapour loss was accounted for by adding the estimated loss of Hg in the form of HgTe in the Te-rich solution. The physical parameters such as surface morphology, composition, thickness, full width at half maximum (FWHM) of double crystal X-ray diffraction (DCXRD) rocking curve and broadening parameters from electrolyte electroreflectance (EER) are given. The effect of growth rate on the crystalline quality is investigated. It is shown by X-ray diffraction and electrolyte electroreflectance measurements that the quality of an epilayer deteriorates when the epilayers are grown at a cooling rate in excess of 2°C h− 1.

Effect of gamma ray and high-energy oxygen ion radiation on electrical and optical properties of MCT epitaxial layers

Hg1-xCdxTe epitaxial layers grown from Te-rich solution have been exposed to Gamma ray radiation up to 650 Grey using Co60 and high energy oxygen radiation at 100Mev. The electrical resistivity, carrier density and Hall mobility values at 77K and IR transmission at 300K have been measured in n,p and compensated epilayers both before and after irradiation. These properties are very much affected by these radiations. In the uncompensated p-type epitaxial layers both types of radiation produced an increase in extrinsic carrier density and a corresponding decrease in Hall mobility. It is observed that both types of radiation have significant effect on the compensated layers and the degree of compensation is greatly reduced by the oxygen irradiation. The 100 Mev oxygen irradiation produced an apparent shift in the bandgap towards shorter wavelength and the absorption below the energy gap is reduced as shown by FTIR measurements, whereas Gamma ray radiation up to the dose 650 Grey did not have any effect on optical properties. These results show the ability of oxygen radiation to passivate the activity of residual impurities or defects.

Growth and characterization of Hg1-xCdxTe epitaxial films by isothermal vapour phase epitaxy (ISOVPE)

Growth of Hg1-xCdxTe epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have been successfully solved. The epitaxial films have been electrically characterized by using the Hall effect and capacitance-voltage (C-V) measurements.

Epitaxial growth from Te rich solution and junction formation in mercury cadmium telluride

Abstract not available.