InAs nanowire growth modes on Si (111) by gas source molecular beam epitaxy

• InAs nanowires were grown on Si by gas source molecular beam epitaxy (GS-MBE).
• Various growth modes of InAs nanowires by GS-MBE were investigated.
• Results from GS-MBE were compared with solid-source MBE.
• Selective area epitaxy of InAs nanowires was extensively investigated.
• Effect of growth temperature, V/III flux ratio, and pattern pitch was studied.

InAs nanowires (NWs) were grown on silicon substrates by gas source molecular beam epitaxy using five different growth modes: (1) Au-assisted growth, (2) positioned (patterned) Au-assisted growth, (3) Au-free growth, (4) positioned Au-assisted growth using a patterned oxide mask, and (5) Au-free selective-area epitaxy (SAE) using a patterned oxide mask. Optimal growth conditions (temperature, V/III flux ratio) were identified for each growth mode for control of NW morphology and vertical NW yield. The highest yield (72%) was achieved with the SAE method at a growth temperature of 440 °C and a V/III flux ratio of 4. Growth mechanisms are discussed for each of the growth modes.