REVIEW OF GROUP-V AMORPHOUS SEMICONDUCTORS

Abstract
The properties of the Group-V amorphous semiconductors, P, As and Sb, are reviewed with particular emphasis on data obtained recently. On the structural side, evidence in favour of CRN models is obtained by consideration of the first sharp diffraction peak at ~ 1Å^-1 and also NQR data which seem to demand a broad distribution of dihedral angles. New results of time-resolved luminescence and ODMR for a-P reveal two channels for recombination, one of which is via a triplet exciton state. The effects of chemical modification and alloying on the electrical and optical properties of a-As indicate that the Fermi level can be shifted, but not to the extent that it can in a-Si : H ; surprisingly hydrogenation makes dopants less effective. Information from Raman and infrared studies concerning vibrational properties is considered and finally the temperature variations of specific heat and ultrasonic attenuation are presented and discussed.