等温気相成長法によりCdTe基板上に成長したHg_<1_x>Cd_xTe層の光応答

概要

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Hg_<1_x>Cd_xTe is a narrow gap semiconductor of II-VI group mixed compound between HgTe and CdTe. In recent applications, Hg_<1_x>Cd_xTe (x≅0.2) has been used as a photo detector for the infrared region around 10μm, and are expected for a large area Infrared Charge Coupled Device (IRCCD). But for the application, there are problems about its uniformity within a plane. Then several epitaxial methods have been developed to get over the problems. In this research, Hg_<1_x>Cd_xTe layers are grown by Isothermal Vapour Phase Epitaxy (ISOVPE) method on CdTe (111) substrates. In the ISOVPE method, no special expensive equipements like in MBE method are not needed. Hg_<1_x>Cd_xTe layers which have graded gap band structures along the growth direction are obtained. The photoresponses as photoconductive detectors are observed at the liquid N_2 temperature using Fourier Transform IR spectrometer (FT-IR). The layers present characteristic two types of photoresponses according to the growth temperatures. One type of specimen shows a sharp response within a narrow wavelength region, and another type shows a relatively wide response like a bulk Murcury Cadmium Telluride (MCT) of x=0.2. By controlling the type of these photoresponses, the useful photo detectors will be available.
東海大学の論文