GROWTH OF ZINC SELENIDE SINGLE-CRYSTAL BY THE MODIFIED PIPER AND POLICH SUBLIMATION METHOD

A high-quality zinc selenide (ZnSe) single crystal was grown in a two- stage vertical electric furnace by the Piper and Polich sublimation me thod with an asymmetric temperature profile around a peak temperature. The growth of the single crystal was optimized at the temperature dif ference of 13 degrees C between the source and growth parts in the gro wth tube. The temperature difference was in good agreement with the ca lculated value of 135.018 degrees C. The diffraction patterns shows th at the single crystal exhibits a zinc blende structure with a lattice constant of 5.627 Angstrom. The measured carrier concentration and mob ility of the as-grown ZnSe single crystal are 4.92 x 10(8) holes cm(-3 ) and 4.40 x 10(3) cm(2)/V s at room temperature, respectively. We not ice that the energy band gap obtained from photocurrent measurements f ollows Varshni's formula E-g,(T) = 2.808 eV - (8.69 x 10(-4) eV/K){T-2 /(T + 330)} rather than a linear relationship E-g(T) = 2.83 eV (8.0 x 10-4 eV/K)T. (C) 1998 Elsevier Science B.V. All rights reserved.