COMPARATIVE-STUDIES OF SI-DOPED N-TYPE MOVPE GAAS ON GE AND GAAS SUBSTRATES

Comparative studies of silicon (Si) incorporation in GaAs on both pola r GaAs and nonpolar Ge substrates by low temperature photoluminescence (LTPL) spectroscopy were carried out. The PL spectrum shifts towards higher energy with growth temperature, arsine (AsH3) and trimethylgall ium (TMGa) mole fractions on Ge substrates; whereas the PL spectrum sh ifts towards higher energy with growth temperature and shifts to lower energy with AsH3 and TMGa mole fractions on GaAs substrates. The shif t in PL peak energy towards the higher energy is due to the increase i n electron concentration The full width at half maximum (FWHM) increas es with increasing growth temperature, AsH3 and TMGa mole fractions on Ge substrates. But the FWHM increases with increasing growth temperat ure and decreases with increasing AsH3 and TMGa mole fractions on GaAs substrates. A vacancy control model may explain the PL peak shift tow ards higher energy with increasing AsH3 mole fraction on Ge substrates and with increasing TMGa mole fraction on GaAs substrates. The experi mental results of the studies of the effect of TMGa mole fraction vari ation on zinc (Zn)-doped GaAs on both GeAs and Ge substrates were pres ented for better understanding of the growth process. (C) 1998 Elsevie r Science S.A. All rights reserved.