SURFACES, INTERFACES, AND THIN FILMS Differential Capacitance of a p + -p Junction

temperature T = 300 K, the capacitance of a p + -p junction increases with an increase in the forward cur� rent, and changes the sign from positive to negative with an increase in the reverse current. At tempera� tures T ≥ 310 K, the p + -pjunction capacitance reaches its maximum with an increase in the forward current, and then decreases and changes sign. The theory of h-l junctions (2-6) cannot explain this change in the character of the current dependence of the p + -pjunction capacitance when the junction temperature is increased. In this context, our purpose was to investigate the dependences of the differential capacitance and cur� rent of the p + -p junction on the junction voltage. The p + -pjunction capacitance, formed by charge redistri� bution in the junction region, is considered taking into account the change in the electric field in the quasi� neutral ptype region in both forwardand reverse� bias modes. The field in the quasineutral ptype region of a forwardbiased p + -pjunction is deter� mined with the dependence of bipolar drift mobility on the concentration of nonequilibrium electron- hole pairs taken into account. It is shown that the change in the character of the dependence of the p + -pjunction capacitance on the injection current with an increase in the junction tem� perature is due to a decrease in the bipolar drift mobil� ity in the ptype region when the conductivity of the latter becomes close to intrinsic one. It is also shown that the change in the sign of the p + -pjunction capacitance with an increase in the reverse current is caused by charge reduction in the junction region due to the dominance of the increase in the negative charge of acceptor ions over the increase in the positive charge of holes. Abstract—The differential capacitance of a p + -p junction formed by charge redistribution near the junction, has been investigated taking into account the electric field in the quasineutral p region. The dependence of the capacitance and current of the p + -p junction on its voltage is obtained. It is shown that a change in the sign of the p + -pjunction capacitance with an increase in the injection level is caused by a decrease in the bipolar drift mobility in the ptype region. It is also demonstrated that a change in the sign of the p + -pjunc� tion capacitance with an increase in the reverse voltage determines the charge reduction near the junction, as the increase in the negative charge of acceptor ions predominates over the increase in the positive charge of holes.