Structural, electrical, and optical property studies of indium-doped Hg 0.8 Cd 0.2 Te/Cd 0.96 Zn 0.04 Te heterostructure
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Structural, electrical, and optical property studies of indium-doped Hg0.8Cd0.2Te/Cd0.96Zn0.04Te heterostructures M.S. Han and T.W. Kanga) Department of Physics, Dongguk University, Seoul 100-715, Korea
T.W. Kim Department of Physics, Kwangwoon University, Seoul 139-701, Korea (Received 11 September 1997; accepted 4 February 1999)
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 Hg0.8Cd0.2Te epitaxial layers grown on Cd0.96Zn0.04Te (211) B substrates by molecular-beam epitaxy. The TEM measurements showed that high-quality Hg0.8Cd0.2Te epitaxial layers with interfacial abruptnesses were grown on the Cd0.96Zn0.04Te substrates. The Van der Pauw Hall effect measurements on typical indium-doped Hg0.8Cd0.2Te/Cd0.96Zn0.04Te 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 Hg0.8Cd0.2Te/Cd0.96Zn0.04Te 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 Hg0.8Cd0.2Te/Cd0.96Zn0.04Te 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 Hg0.8Cd0.2Te epitaxial layers were high-quality n-type layers and that p-HgxCd1–xTe epilayers can be grown on indium-doped Hg0.8Cd0.2Te/Cd0.96Zn0.04Te heterostructures for the fabrication of HgxCd1–xTe photoconductors and photodiodes.
I. INTRODUCTION
Hg1–xCdxTe thin films have attracted attention because of their potential applications in the area of the infrared detectors.1 The growth of n-type and p-type Hg1–xCdxTe epitaxial films were interfacial abruptnesses on the scale of a few lattice constants has been particularly attractive because of many promising applications for infrared focal-plane array technology.2–9 However, Hg0.8Cd0.2Te infrared photodetectors functioning in the wavelength range of 8–12 m have low junction resistivities and high surface leakage currents.4 Until now, liquid-phase epitaxy and metalorganic chemical vapor deposition have been used to grow Hg1–xCdxTe epitaxial films.5 However, because the samples grown by those methods have interface problems, a molecular-beam epitaxy (MBE) growth method has been introduced to overcome the problems. Furthermore, with use of the MBE method,
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http://journals.cambridge.org
J. Mater. Res., Vol. 14, No. 7, Jul 1999 Downloaded: 13 Mar 2015
high-quality Hg1−xCdxTe epitaxial films can be grown at low temperature, and the n- and p-type films can be grow
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