Direct Observation of Gaussian-Type Energy Distribution for Hot Electrons in Silicon

Abstract

Measurement of photon emission spectra from metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and reverse biased pn junctions at room temperature reveals that electron energy distribution is expressed by a Gaussian distribution function rather than the commonly used Maxwellian distribution function at high electric field: Gaussian distribution function decreases more rapidly in the high energy tail than the Maxellian distribution for the same average energy. The energy relaxation time, τe=0.17 ps, extracted from the optical measurements is much shorter than calculated values by Monte Carlo simulation, τe0.5∼1.0 ps, while it is longer than the recently reported experimental values (τe0.06∼0.10 ps). The discrepancy between the relaxation time obtained here and from other experiments is due to the fact that Maxwellian distribution has been erroneously assumed to evaluate the energy relaxation time in the high-energy tail in the previous works.