Selective Area Growth of High-Quality In-Plane GaAs Nanowires and Nanowire Networks by Molecular Beam Epitaxy on Ge Substrates

Anti-phase domain defects easily form in the in-plane GaAs nanowires (NWs) grown on CMOS-compatible group IV substrates, which makes it difficult to obtain GaAs NWs with a designed length and also leads to a significant limitation in the growth of high-quality in-plane GaAs NW networks on such substrates. Here, we report on the selective area growth of anti-phase domain-free in-plane GaAs NWs and NW networks on Ge (111) substrates. Detailed structural studies confirm that the GaAs NW grown using a large pattern period and GaAs NW networks grown by adding the Sb are both high-quality pure zinc-blende single crystals free of stacking faults, twin defects, and anti-phase domain defects. Room-temperature photoluminescence measurements show a substantial improvement in crystal quality and good consistency and uniformity of the GaAs NW networks. Our work provides useful insights into the controlled growth of high-quality anti-phase domain-defects-free in-plane III-V NWs and NW networks.