Comparative studies of Si-doped n-type MOVPE GaAs on Ge and GaAs substrates

Comparative studies of silicon (Si) incorporation in GaAs on both polar 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 trimethylgallium (TMGa) mole fractions on Ge substrates; whereas the PL spectrum shifts towards higher energy with growth temperature and shifts to lower energy with AsH3 and TMGa mole fractions on GaAs substrates. The shift in PL peak energy towards the higher energy is due to the increase in electron concentration The full width at half maximum (FWHM) increases with increasing growth temperature, AsH3 and TMGa mole fractions on Ge substrates. But the FWHM increases with increasing growth temperature and decreases with increasing AsH3 and TMGa mole fractions on GaAs substrates. A vacancy control model may explain the PL peak shift towards higher energy with increasing AsH3 mole fraction on Ge substrates and with increasing TMGa mole fraction on GaAs substrates. The experimental results of the studies of the effect of TMGa mole fraction variation on zinc (Zn)-doped GaAs on both GaAs and Ge substrates were presented for better understanding of the growth process.