Structural, electrical, and optical property studies of indium-doped Hg_0.8Cd_0.2Te/Cd_0.96Zn_0.04Te heterostructures

Abstract

Transmission electron microsopy (TEM), Hall effect, and Fourier transform infrared (FTIR) transmission measurements were performed to investigate the structural, electrical, and optical properties of indium-doped Hg_0.8Cd_0.2Te epitaxial layers grown on Cd_0.96Zn_0.04Te (211) B substrates by molecular-beam epitaxy. The TEM measurements showed that high-quality Hg_0.8Cd_0.2Te epitaxial layers with interfacial abruptnesses were grown on the Cd_0.96Zn_0.04Te substrates. The Van der Pauw Hall effect measurements on typical indium-doped Hg_0.8Cd_0.2Te/Cd_0.96Zn_0.04Te heterostructures with a doping concentration of 6 × 10¹⁶ cm⁻³ at 10 K in a magnetic field of 0.5 T yielded a carrier density and a mobility of 2.2 × 10¹⁶ cm⁻³ and 40,000 cm²/V s, respectively. The FTIR spectra showed that the absorption edges of the indium-doped Hg_0.8Cd_0.2Te/Cd_0.96Zn_0.04Te heterostructures shifted to a shorter wavelength range than those of the undoped samples, which was caused by the Burstein–Moss effect. The FTIR spectra also showed that the transmittance intensities of the indium-doped Hg_0.8Cd_0.2Te/Cd_0.96Zn_0.04Te heterostructures increased compared with those of the undoped heterostructures, which is due to the compensation of the Hg vacancy defects by the indium atoms. These results indicate that the indium-doped Hg_0.8Cd_0.2Te epitaxial layers were high-quality n-type layers and that p-Hg_xCd_1−xTe epilayers can be grown on indium-doped Hg_0.8Cd_0.2Te/Cd_0.96Zn_0.04Te heterostructures for the fabrication of Hg_xCd_1−xTe photoconductors and photodiodes.