Experimental study on the velocity and the shape of high field domains moving in the anode–cathode direction in CdS crystals

Abstract

A sensitive method for contactless measurements of the electric field strength in CdS (which is applicable for other wide‐gap semiconductors, too) was used to investigate the main parameters of ac high field domains in monocrystalline CdS platelets. The field distribution in the ac domains and the domain velocity were measured in dependence on the intensity of green and infrared (ir) light and on the applied voltage. The occurrence of ac domains under inhomogeneous ir irradiation and double‐injection conditions was observed. The experimental results indicate that holes play an important role in the behaviour of the ac domains.

An optical method for measuring temperature and electric field in semiconductors

“…The optical method has been successfully applied to investigate the following characteristics of recombination domain instabilities in CdS single crystals (Germanova 1973, 1975, Koepp and Marinova 1972, Marinova 1973. 6) or (7), do not differ essentially, the experimentally obtained dependence A p , T(t) provides direct information about the domain shape.…”

“…Due to the slight field shift of the absorption edge, the electric field may be measured by using the optical method under some restrictions. It follows from equation (4') that at T= To (7) which coincides with equation ( 5) of Koepp and Marinova (1972). The admissible deviation (AT) of T from TO (T= TO + AT) may be evaluated on the basis of equations (4') and ( 7):…”

On the electrical instabilities in CdS crystals

“…Xote also that the a-c waves were usually observed when the I-U characteristic is slightly non-ohmic and therefore it is reasonable to suppose a field-dependent conductivity. There is experimental evidence of Koepp and Marinova [5] and Gernianova and Marinova [ll] showing that double injection is present in some crystals doped with Co during the growth and contacted with In-Ga eutectic. The I-U characteristic in this case is shown on Fig.…”