Bismuth Surfactant Effects for GaAsN and Beryllium Doping of GaAsN and GaInAsN Grown by Molecular Beam Epitaxy

Bi was investigated as a possible surfactant for growth of GaAs_1-xN_x layers on (1 0 0) GaAs substrates by molecular beam epitaxy (MBE) using a radio frequency (RF) plasma nitrogen source. Importantly, Bi extends the useable growth conditions producing smoother surfaces to a significantly higher group V fractional N content than without Bi, enhancing possibilities for growth of structures requiring a larger nitrogen content. The conductivity of Be-doped GaAsN and GaInAsN decreased significantly with increasing N concentration. Temperature-dependent Hall measurement suggests possible compensation and increased activation energy. SIMS and Raman measurements indicate that the N composition increased with introducing Be, and for low [N], with the presence of Bi. The addition of Bi during growth of Be-doped GaAsN only produced semi-insulating layers at all concentrations investigated suggesting it enhances the formation of compensating defects.