Studies on growth mechanism of HgCdTe epilayer on Si grown by HWE

Abstract

In this paper, the mechanism of Hg_1−xCd _x Te/Si heterojunction grown by HWE (Hot Well Epitaxy) was studied. Opitical characterizations were shown with FTIR, the composition x = 0.39 was deduced by using MIR transmittance, the absorbing peak at 319.4 cm⁻¹ was measured by FIR transmittance, 319.4 cm⁻¹ confirmed the existence of Si–Te bond of at Si/HgCdTe interfacial layer. The I-V characteristics at both room temperature and 77 K of HgCdTe (n-type)/Si (p-type) heterojunction show that the good p-n heterojunction properties was obtained by using HWE. XRD study confirmed the formation of (111) oriented HgCdTe on (211) Si. Morphology of a cross section observed using EPMA indicates the columnar growth of HgCdTe. An analysis of interfcial layer by EPMA indicated presence of three layers composed of Si + Te, Si + Te + Hg and Si + Te + Cd + Hg. Among them, the most important one is the first layer. The problem of lattice mismatch and the difference of thermal expansion coefficient between Si and CdTe or HgTe may be improved by formation of Si–Te stable chemical bond through bybridization orbital bonding between Si and Te. The second and third layers are formed by evaporation-interdiffusion. Formation of the whole interfacial layer provides the appetency for the growth of (111) Hg_1−xCd _x Te epilayer on (211) Si substrate.