Temperature Dependence of Double Injection in a Long Silicon p+-π-n+ Structure

Abstract

Current-voltage characteristics from 140° to 350°K are measured on a long p+-π-n+ silicon structure biased into the double-injection regime. The I-V characteristics obey a J ∝ V2/L3 relation throughout the considered temperature range, and the magnitude of the double-injection current is predicted within 10% by the Lampert expression J = (9/8) qμpμnτ (p0-n0) V2/L3. The transient response of double injection as analyzed by Baron provides a direct measure of the common high-level lifetime τ, which is given by the formula τ=30.7×10−6 (T/298)1.93±0.23 sec. Conductivity, Hall effect, and the large-signal-step-response method of Dean establish the electron and hole mobility as μn=1280 (298/T)1.75±0.31 cm2/V-sec and μp=410 (298/T)2.18±0.04 cm2/V-sec, respectively, for 140°≤T≤350°K. The consistency between the measured values of the lifetime and mobilities with values reported by the literature establishes that the temperature dependence of a long double-injection p+-π-n+ silicon device is in agreement with the Lampert expression and the temperature variation of τ (T), μp(T), and μn(T). A 14-MeV neutron irradiation of 1.25×1011 n/cm2 does not alter the quadratic law J ∝ V2/L3 of the device but results in lower current levels when compared to the preirradiation condition. Pulse and dc measurements analogous to the preirradiated case give τ̂=8.9×10−6(T/298)0.68±0.07 sec, μ̂p=385(298/T)1.30±0.10 cm2/V−sec, and μ̂n=1160(298/T)1.28±0.21 cm2/V−sec for the carrier lifetime and mobilities, respectively. After irradiation reasonable agreement is found between the measured double-injection current and that predicted from Baron's first-order correction of the Lampert expression for diffusion and thermal generation effects.