Fast Growth of Smooth AlN in a 3 × 2″ Showerhead‐Type Vertical Flow MOVPE Reactor

Abstract

The conditions required for a high growth rate of AlN in a 3 × 2″ showerhead‐type vertical flow metalorganic vapor phase epitaxy (MOVPE) reactor are studied. It is found that at the standard growth conditions (low V/III, 50 mbar, 1110 °C, H2), the growth rate linearly increases with the trimethylaluminium (TMAl) flow rate until about 280 μmol min−1 with some drop of precursor utilization efficiency at higher pressures. While the pre‐reaction of TMAl with NH3 at 140 μmol min−1 of TMAl is still not a major issue, it is not possible, however, to maintain a smooth AlN surface morphology during this “fast” growth. To suppress the surface morphology deterioration, the growth pressure requires optimization. An increase of the growth pressure, to 75 mbar, is found to be critical to grow 20+ μm of smooth AlN at a rate of about 3.6 μm h−1 on bulk AlN substrates.

Organized AlN Nanowire Arrays by Hybrid Approach of Top-Down Processing and MOVPE Overgrowth for Deep UV Emission Devices

“…Here, two types of MOVPE growth conditions are investigated for AlN overgrowth. The first one is chosen to be similar to the usual growth conditions of planar c -oriented AlN: , growth under a H 2 atmosphere at 1200 °C and 100 mbar using TMAl and NH 3 precursors with respective fluxes of 7.36 and 2230 μmol min –1 , corresponding to a low V/III ratio equal to 300 (sample called “low V/III”). The second one is the same except for the NH 3 flux, which is now 201 000 μmol min –1 leading to a significant V/III ratio equal to 27 000 (sample called “high V/III”), in accordance with the already reported AlN overgrowth on wire geometry. , The growth time is 1 h 30 min for both samples, corresponding to the deposition of approximately 225 nm AlN for the high V/III recipe and 190 nm AlN for the low V/III one (for the S = 5 μm and D initial = 500 nm pillars).…”