Some Optical Properties of Cadmium Telluride

Some optical properties of CdTe samples having a carrier concentration of the order of ${10}^{15}$ ${\mathrm{cm}}^{-3\mathrm{}}$ were measured. The index of refraction in the infrared was determined to be 2.61. Values of the absorption coefficient $\alpha$ as a function of frequency were obtained at various temperatures. By plotting ${\alpha }^{\frac{1}{2}}$ and ${\alpha }^2$ against frequency, it was found that at room temperature the minimum energy for direct transitions is 1.50 ev; that for indirect transitions is 1.44 ev. The temperature dependencies between 77°K and 373°K are given by ($1.66-5.6\times {10}^{-4\mathrm{}}T$) ev for direct transitions and ($1.56-4.1\times {10}^{-4\mathrm{}}T$) ev for indirect transitions.