DISTRIBUTION OF RECOMBINATION CENTERS PRODUCED BY BOMBARDMENT OF SILICON WITH MODERATE-ENERGY IONS.

A study was made of the distribution of recombination centers with depth in silicon bombarded with N** plus and Ar** plus ions of 50 keV energy. This distribution was determined by measuring the surface photo-emf in the course of electrochemical dissolution of Si. A study was made of the influence of the radiation dose and annealing temperature on the shape of the distribution curves of recombination centers. The rise of the concentration of these centers as a result of ion bombardment was limited by the formation of complexes. The dissociation of the complexes during annealing generated recombination centers which were stable in a certain range of temperatures. The experimental distributions were compared with those calculated by the Monte Carlo method. It was found that the rate of accumulation of the centers near the very surface differed from the rates of accumulation in the region corresponding to the maximum in the calculated defect distribution and in the region between this maximum and the surface. These differences led to layered amorphization at sufficiently high defect concentration. Measurements of the electrode potentials gave information on the distribution of charged centers associated with radiation defects. The concentration of these centers reached saturation at a dose equal to the amorphization dose.