Selective area vapor-phase epitaxy and structural properties of Hg1 − xCdxTe on sapphire

Abstract

Selective area (SA) Hg1 − xCdxTesapphire layers have been grown using the recently developed technique of the vapor-phase epitaxy (VPE) of Hg1 − xCdxTe layers on CdTesapphire heteroepitaxial substrates (HS), which we have called “VPE on HS technique” (Sochinskii et al., J. Crystal Growth 149 (1995) 35; 161 (1996) 195). First, planar CdTe (1 1 1) 5–7 μm thick layers were grown on sapphire (0 0 0 1) wafers by metalorganic vapor-phase epitaxy (MOVPE) at 340°C for 1–2.5 h using dimethylcadmium and di-isopropyltellurium as precursors. Second, CdTe/sapphire mesas were formed using standard photolithography in the form of alternating parallel linear arrays consisting of 500 × 70 μm2 elements. Third, SA Hg1 − xCdxTesapphire 17–23 μm thick layers with the composition x = 0.3 were obtained by the VPE of HgTe on the CdTe/sapphire mesas at 530°C for 60–90 h which was followed by the interdiffusion of Hg and Cd. Results on the structure characterization of the SA Hg1 − xCdxTesapphire layers by scanning electron microscopy, synchrotron X-ray topography and Rutherford backscattering spectrometry are reported. The layers were found to have a good single-crystalline quality and uniform composition over the entire substrate area. The structural properties of the SA Hg1 − xCdxTesapphire layers are compared with those of the planar layers grown by the VPE on HS technique under similar experimental conditions.