Structural defects in Hg1−xCdxI2 layers grown on CdTe substrates by vapor phase epitaxy

Abstract

Hg 1Ϫx Cd x I 2 20-25-m-thick layers with a uniform composition in the range of xϭ0.1-0.2 were grown on CdTe substrates by vapor phase epitaxy ͑VPE͒. The growth was carried out using an ␣-HgI 2 polycrystalline source at 200°C and in the time range of 30-100 h. The layers were studied by scanning electron microscopy ͑SEM͒ and high resolution synchrotron x-ray topography ͑SXRT͒. The SEM and SXRT images of Hg 1Ϫx Cd x I 2 VPE layers allow one to identify the defects affecting the layer structure. The two main types of structural defects in the layers are subgrain boundaries and densely spaced striations similar to those referred generally to as vapor grown HgI 2 bulk crystals. The effect of the growth time on these defects has been analyzed and on the basis of this it has been possible to grow Hg 1Ϫx Cd x I 2 layers with low defect density.

Combined photoluminescence study of substrate defects in Hg1−xCdxI2/CdTe heterostructures

“…1b, shows the Hg 1Àx Cd x I 2 layer (I), the specific polycrystalline area (II) related to the VPE growth kinetics and a sharp layer/substrate interface. More details on the Hg 1Àx Cd x I 2 layer structure in dependence on the VPE growth conditions could be found elsewhere [6,12,15,16]. 2 shows the PL spectra of CdTe substrate, which were measured on its cleaved cross-section (a, b) and surface through the Hg 1Àx Cd x I 2 layer (c).…”

“…Among numerous growth techniques and post-growth treatment methods, which are actually used to obtain these materials, lowtemperature ones are of great concern because they permit to reduce the problems arising from the high residual concentrations of native structural defects [3][4][5][6][7][8][9][10]. In some cases, a combination of different materials in a unique heterostructure, e.g.…”