VAPOR-PHASE EPITAXY OF HG1-XCDXI2 LAYERS ON CDTE SUBSTRATES

Vapor phase epitaxy (VPE) has been studied to grow Hg1-xCdxI2 epitaxia l layers on CdTe bulk substrates. The effect of the VPE growth conditi ons on the morphology, composition and crystalline quality of Hg1-xCdx I2/CdTe heterostructures has been investigated. It has been shown that 10-30 mu m thick Hg1-xCdxI2 layers can be successfully grown using an alpha-HgI2 polycrystalline source under isothermal conditions at a te mperature in the range 170-240 degrees C for the time period 20-50 h. Interestingly, the VPE growth was found to consist of two successive s tages with different kinetics as follows: (1) a fast growth of an HgI2 platelet layer on the CdTe substrate surface and (2) a slow growth of an Hg1-xCdxI2 layer on the surface of the platelet layer. The Hg1-xCd xI2 layers exhibited single-crystalline structure when the layer compo sition has been varied in the wide range x = 0.24-0.67. The particular role of the HgI2 platelet layer morphology in controlling the composi tion uniformity throughout the thickness of the Hg1-xCdxI2 layer has b een demonstrated.