Use of high temperature hydrogen annealing to remove sub-surface damage in bulk GaN

Cathodoluminescence evaluation of subsurface damage in GaN substrate after polishing

“…This result indicates that the annealing with such gas mixtures produced an inhomogeneous etching effect on the surface, and enhanced the damages caused by the polishing process. Similar results were reported earlier in [9] where a rougher surface of bulk GaN was observed after the annealing with pure H 2 at similar temperatures. Mastro et al also performed annealing of HVPE GaN layers with H 2 at different temperatures [11].…”

“…The thermal treatment was carried out in a metal organic chemical vapor deposition (MOCVD) system. Since the annealing with N 2 or N 2 plasma treatment was reported to produce smoother surface [6], while the annealing with H 2 tended to result in rougher surface [9], thermal annealing with different gas mixtures were tested in order to compare the surface morphologies and the effects on subsurface damages. Two samples (A and B) grown under different conditions [10], but with identical polishing procedure (Procedure 1) were annealed at different gas conditions: Sample A was annealed with the gas mixture of NH 3 , H 2 and N 2 , while Sample B was annealed with the mixture of NH 3 and N 2 .…”

Hydrogen etching on the surface of GaN for producing patterned structures

“…It is proposed from the previous studies that H 2 enhances GaN decomposition [8]. H and N atoms combine to form NH 3 at high temperature, and then liquid Ga is subsequently left on the surface [8,11,12]. Ga droplet will remain as long as the Ga desorption rate is not high, which has been observed in our low temperature experiment.…”

Study on optimal growth conditions of a-plane GaN grown on r-plane sapphire by metal-organic chemical vapor deposition

“…The high V/III ratio led to high NH 3 flow and further produced more amounts of hydrogen during the growth process. Some pits distributed on the surface, under the high V/III ratio, could be due to the excess hydrogen facilitating the surface dissociation rate and damaging the surface morphology [15]. Although the low V/III ratio condition benefits the 2D growth, some Ga atoms would not react with insufficient N atoms causing a wavy surface.…”