D Aladashvili, Z Adamia, A Adamia
The dependence of the shape of current oscillations observed in the hopping conductivity region in a weakly compensated p-Si on the supply voltage applied to the sample is established. With increasing bias voltage the current pulse shape to form a hopping domain changes significantly. The change in the shape is ascribed to voltage redistribution in corresponding regions in the bulk of the crystal. In [1] the observation of a new type of current instability in the hopping conductivity region was
more » ... uctivity region was reported. The phenomenon manifested itself in a periodic current increase and decrease observed in the external electric circuit. The current oscillations were observed in samples with a sublinear current-voltage characteristic in the portion with a negative differential resistance. A slight decrease in the conductivity with increasing field was obtained experimentally in p-Ge [2]. Earlier in [3] a possibility of exponential decrease in the hopping conductivity with increasing field had been predicted. In the work a formation of dead ends in the infinite cluster (IC) of acceptors responsible both for electron trapping in high electric fields and for hopping transport was considered. The length of these ends-traps was equal to that of the characteristic grid period. A statistical current-voltage characteristic with decreasing current was computer-modeled [4] in assumption of an ideally homogeneous sample. In this case typical traps captured electrons in any part of the sample with equal probability. And the real sample always has an inhomogeneity of one kind or another. Further experimental investigations showed that current oscillations observed in the semiconductor were due to formation and motion of a hopping domain in the bulk of the sample [5]. A crystal "predisposed" to negative differential resistance passes into this state in the portion where its resistance is somewhat higher. 153