Effect of hydrogenation on the electrical and optical properties of CdZnTe substrates and HgCdTe epitaxial layers

Surface morphology of Hg0.8Cd0.2Te epilayers grown by LPE using horizontal slider

Effects of microgravity on Hg1−xCdxTe/(100)CdTe epitaxy by CVT under transient growth conditions

Second-harmonic (SH) rotational anisotropy measurements performed on epitaxial (CMT) layers grown on CdTe B substrate exhibits an interference in the SH signal originating from the bulk and from the CMT surfaces. The threefold symmetry of the epilayer was shown to be sensitive to the nature of adsorbed species at the surface when in contact with an electrolyte solution despite the strong SH generation in the bulk of the layer. The modification of the SH response from a non-centrosymmetric semiconducting material to such an extent is unusual since bulk SH generation is considered as the dominant contributor in these instances. The case of CMT is, however, rather specific in that the observed SH signal originates from, at most, only the top 40 nm of the CMT epilayer. This important difference means that surface modification by means of electron donating or withdrawing groups will play a large role in the observed SHG signal.

Second-harmonic generation in the characterization of surface effects in 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.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

S. Sitharaman

Papers

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