Ultra-flat AlN grown with a pulsed H₂ etching condition

Abstract

A 1.5 μm AlN epilayer with a root-mean-square surface roughness of 0.25 nm was grown by metal-organic chemical vapor deposition at the single substrate temperature below 1200 °C. The ultra-flat surface is achieved with 30 min annealing performed in the initial growth, during which abrupt AlN hillocks are removed by pulsed H2 etching controlled via the on/off duration of NH3 supply. The pulsed etching technique effectively tailors the island-like morphology of the AlN buffer, facilitating the lateral crystal nucleation in subsequent growth. This study provides a simple, feasible and cost-effective manufacturing method for high-quality AlN.

Crystal Transformation of Cubic BN Nanoislands to Rhombohedral BN Sheets on AlN for Deep-UV Light-Emitting Diodes

“…If properly controlled, the catalyst-like etching/regrowing process induced by H 2 is expected to improve the crystal quality of BN by removing the vacancy defects on the epitaxial surface. 18,36 Our observation of high BN qualities with reduced V/III ratios seems to oppose the results reported by Kobayashi et al, 29,41 who found that the qualities of hBN were improved by increasing the V/III ratio in MOCVD growth. The inconsistency can be due to the fact that the MOCVD is a complex chemical process, and various factors may influence the crystal quality to a certain extent, depending on the hardware design and the adopted growth conditions.…”

“…As the NH 3 flow is reduced to lower the V/III ratio, the H 2 gas supplementarily injected to the reactor can raise the etching rate of the defective B–N bonds, followed by the regrowth from the bonding between B and N ions. If properly controlled, the catalyst-like etching/regrowing process induced by H 2 is expected to improve the crystal quality of BN by removing the vacancy defects on the epitaxial surface. , …”

“…BN and AlN were both attained at the single substrate temperature of 1180 °C and a reactor pressure of 25 mbar. Details of the AlN growth can be found in our previous publications. , Scheme illustrates the growth process of BN. Trimethylaluminum (TMAl), triethylboron (TEB), and ammonia (NH 3 ) diluted in the carrier gas (H 2 ) were employed for Al, B, and N precursors, respectively.…”

Si‐Doping Effects in AlGaN Channel Layer on Performance of N‐Polar AlGaN/AlN FETs

“…We succeeded in significantly improving the flatness of N-polar AlN grown on a sapphire substrate with a misorientation angle of 2.0°using periodic pulsed H 2 etching. [8,[20][21][22] Furthermore, we used N-polar AlN to successfully fabricate a N-polar AlGaN/AlN heterostructure field-effect transistor (FET) with good static FET characteristics. [23] However, the drain current density, drain-source current (I DS ), remains significantly small.…”

Optical properties of AlN films deposited by energy-filtering magnetron sputtering technique

“…People have tried to synthesize AlN films with different preparation methods, such as CVD, 9) pulsed laser deposition, 10) molecular beam epitaxy, 11,12) metal-organic CVD, [13][14][15] and magnetron sputtering. 16,17) Among them, magnetron sputtering technology is simple and could prepare thin films with high quality, uniformity, repeatability, and excellent adhesion to the substrate.…”