Electroluminescence spectroscopy of AlGaAs/InGaAs and AlGaAs/GaAs high-electron-mobility transistors

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Abstract
Electroluminescence of pseudomorphic InGaAs high‐electron‐mobility transistors (HEMTs) on GaAs and of standard AlGaAs/GaAs HEMTs with ultrashort gate lengths is investigated at room and cryogenic temperatures. The spectral distribution of the emitted radiation is analyzed in the 0.7–1.6 eV energy range. In the case of pseudomorphic transistors, three different recombination lines originating from distinct layers are observed: a broad luminescence band around 0.8–0.9 eV; a doublet arising from confined subbands in the InGaAs layer; and a single peak coming from the GaAs substrate. The energy position and the temperature dependence of these different lines under various biases give valuable information on the physical mechanisms which occur under high‐electric‐field nonstationary transport: lattice self‐heating (≊150 K at high‐bias conditions), origin of the impact ionization in the channel of the quantum‐well layer, and perpendicular transfer of hot holes which recombine with the barrier DX centers thus leading to the broad luminescence band. These characteristics are supported by comparison with analog standard HEMTs and with electrical measurements.