THERMAL GENERATION OF CARRIERS VIA SURFACE CENTERS AFTER NONEQUILIBRIUM SWITCHING OF A METAL-INSULATOR-SEMICONDUCTOR STRUCTURE TO THE INVERSION REGIME.

A study is made of the kinetics of the generation of the minority carriers via surface states after switching a metal-insulator-semiconductor structure from the state of accumulation of the majority carriers on the semiconductor surface to a state of depletion. The system of equations describing the time dependence of the carrier density in the semiconductor bands and in the surface states is solved for the cases of monoenergetic and continuous spectra of surface states, and the relevant analytic expressions are obtained. Three stages of the transient process can be distinguished: a fast exponential change in the charge carried by the surface centers to a quasisteady state, generation of the minority carriers in accordance with linear and then parabolic laws and corresponding quasisteady change in the charge of the surface centers, and exponential relaxation to a steady (equilibrium) state. Most of the minority carriers are accumulated during the second stage of the transient process. The analysis is concluded with a discussion of the experimental methods for investigating the transient process; the most effective method for the determination of the minority-carrier density is the method of dynamic capacitance-voltage characteristics.