Abstract

New results are presented concerning the spectral distribution in the 1.7 - 2.9 eV range of the electromagnetic radiation emitted by 0.5 mm GaAs MESFETs and 0.3 mm AlGaAs/GaAs HEMTs biased at high drain voltages (> 4.0 V). The energy distribution of the emitted light intensity cannot be described by assuming a maxwellian electron energy distribution function. The detection of emitted radiation is markedly correlated with the presence of non-negligible gate and substrate hole currents, which are not due to breakdown of the gate-drain Schottky junction, but are due to collection of holes generated by impact ionization.