MBE-grown GaAs/AlGaAs multiple quantum wells on Ge substrate

Abstract

GaAs/AlGaAs multiple quantum wells (MQWs) on Ge substrate are grown by molecular beam epitaxy and their properties are compared with MQWs on GaAs substrate. The scheme of the growth includes GaAs deposition by migration enhanced epitaxy (MEE) at low-temperature and followed by growth of thin GaAs layer at high temperature and annealed during growth. This mechanism reduced the anti-phase domain disorder and blocked the dislocations. An interesting phenomenon of increase in integrated PL intensity of wells with higher activation energy at higher temperatures is observed and is correlated with simultaneous quenching of PL intensity in wells with lower activation energies. TEM images confirm lack of dislocations in QW layers. X-ray diffraction measurements confirm very good structural. In conclusion, multiple quantum wells grown on Ge substrate have properties comparable to those grown on GaAs substrate.