Catalyst-free growth of semiconductor nanowires by selective area MOVPE

We report on a novel catalyst-free approach to form GaAs, AlGaAs and InGaAs nanowires and their arrays by selective area metalorganic vapor phase epitaxy (SA-MOVPE). At optimized growth conditions, extremely uniform array of GaAs or InGaAs nanowires with diameter d of 100 nm to 200 nm were grown on GaAs and InP substrates, respectively. It was found the the shape (height h and size d) depends strongly on the growth conditions as well as the size do and pitch a of the mask opening. In particular, the height h of the pillar becomes higher as d is reduced. On the other hand, h decreases as a is increased. Based on these results, we obtained hexagonal nanowires with much smaller d (similar to 50 nm) and longer h (> 6 mu m) by doing SA-MOVPE on masked substrates with smaller d(0).