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

The single delta -doped InGaAs/AlGaAs pseudomorphic HEMT structure material s were grown by molecular beam epitaxy. The photoluminescence spectra of th e materials were studied. There are two peaks in the photoluminescence spec tra of the materials, corresponding to two sub energy levels of InGaAs quan tum well. The ratio of the two peak's intensity was used as criterion to op timize the layer structures of the materials. The material with optimized l ayer ;tructures exhibits the 77 It mobility and two-dimensional electron ga s density of 16 500 cm(2)/Vs and 2.58 x 10(12) cm(-2) respectively, and the 300 K mobility and two-dimensional electron gas density of 6800 cm(2)/Vs a nd 2.55 x 10(12) cm(-2) respectively. The pseudomorphic HEMT devices with g ate length of 0.2 mum were fabricated using this material. The maximum tran sconductance of 650 mS/mm and the cut-off frequency of 81 GHz were achieved . (C) 2001 Elsevier Science B.V. All rights reserved.