Effects of Al0.3Ga0.7As interlayer with pulsed atomic layer epitaxy on heterogeneous integration of GaAs/Ge grown by MOCVD

In this paper, high quality GaAs films on Ge (0 0 1) substrates with 9° offcut toward the (1 1 1) plane were grown by metal organic chemical vapor deposition (MOCVD) through adopting the Al0.3Ga0.7As interlayers with pulsed atomic layer epitaxy (PALE) technology. The effects of Al0.3Ga0.7As PALE interlayers with different growth sequences, AlAs/GaAs PALE and AlGa/AlGaAs PALE, on the morphological, structural and optical properties of GaAs epilayers were investigated. The results showed that Al0.3Ga0.7As PALE interlayers were preferred to eliminate anti-phase domains (APDs) and suppress Ge atoms outdiffusion at the heterointerface, effectively. Additionally, AlAs/GaAs PALE, the optimized growth sequence of Al0.3Ga0.7As PALE interlayers, could obtain the smoothest surface morphology (root-mean-square (RMS) 0.43 nm) and best crystalline quality, which was attributed to the control of AsH3 exposure time ensuring fewer As vacancies acting as defect centers.