ZnSb単結晶の製作とその半導性

Abstract

Single crystals of a semiconducting intermetallic compound ZnSb have been grown by Bridgman’s method and Czochralski’s method. Particularly for Czochralski’s method has been used a very simple apparatus to obtain large single crystals more easily than various complex equipments with some difficult techniques which have been reported so far. This compound crystallizes in the orthorhombic structure, and therefore its semiconducting properties should be anisotropic. Then its electronic and optical properties have been carefully studied in the three principal directions; measurements of the resistivity, Hall coefficient, Seebeck coefficient and the infrared absorption of ZnSb single crystals for these directions have been performed as a function of temperature. The results are as follows: (1) The single crystals of ZnSb thus obtained are quite brittle, cleaving readily on the (100) plane and occasionally on the (001) or (010) plane. (2) All of the single crystals are p-type. (3) The energy gap of 0.56 eV at room temperature is obtained from the slope of intrinsic resistivity curves. (4) For the hole mobility, CT−a law holds approximately between 80° and 300°K, and a is 1.4 to 1.6. (5) The mobility ratio found by the method shown in Fig. 12 is 2.2. (6) The effective mass of holes is calculated to be about 0.19 m0 from Seebeck coefficient data. (7) The infrared absorption gives values for the energy gap for indirect transitions of 0.51 eV at room temperature and 0.61 eV at 0°K. (8) The resistivity, mobility and Seebeck coefficient are found to be anisotropic. The three principal mobilities are in the ratio μ[010]:μ[100]:μ[001]=1:2.6−2.9:4.1−4.5 at the temperature of liquid nitrogen.