Using photoluminescence as optimization criterion to achieve high-quality InGaAs/AlGaAs pHEMT structure

Abstract

The single δ-doped InGaAs/AlGaAs pseudomorphic HEMT structure materials were grown by molecular beam epitaxy. The photoluminescence spectra of the materials were studied. There are two peaks in the photoluminescence spectra of the materials, corresponding to two sub energy levels of InGaAs quantum well. The ratio of the two peak's intensity was used as criterion to optimize the layer structures of the materials. The material with optimized layer structures exhibits the 77 K mobility and two-dimensional electron gas density of 16 500 cm 2/V s and 2.58×10 12 cm −2 respectively, and the 300 K mobility and two-dimensional electron gas density of 6800 cm 2/V s and 2.55×10 12 cm −2 respectively. The pseudomorphic HEMT devices with gate length of 0.2 μm were fabricated using this material. The maximum transconductance of 650 mS/mm and the cut-off frequency of 81 GHz were achieved.