Determining Generation–Recombination Characteristics of a Semiconductor–Dielectric Interface from the Current Kinetics of Surface Minority Carrier Generation

Abstract

Conditions for the one-to-one characterization of the generation (Gs) and surface recombination (Rs) rates of minority charge carriers (MCCs) in a metal–oxide–semiconductor (MOS) structure (in the case of strong nonequilibrium depletion) by the MCC surface generation current (I(t)) flowing in an external circuit of this structure are revealed. These conditions are the following: (1) the generation current I is independent of the time t (until the structure enters an equilibrium state) and the voltage Vg0 corresponding to the initial nonequilibrium depletion and (2) the duration of current steps I(Vg0) = const and, consequently, the equilibrium surface charge increase with increasing Vg0. The observed kinetics of the MCC generation current for the MCCs induced in an n-Si MOS structure at 293 K experimentally confirms the realization of these conditions. The values of the generation and recombination rates Gs = 2.84 × 1010 cm–2s–1 and Rs = 6.82 cm s–1 obtained from current levels I(Vg0) = const are typical of high-quality Si MOS structure. Additionally measured capacitance–voltage characteristics were used to determine the interface state density at the Si/SiO2 contact near the middle of the Si gap (Nss(E) ≅ 6.4 × 1010 cm–2eV–1), which allowed the estimation of the effective capture cross section of these states σ eff ≅ 1.4 × 10–16 cm2.