Uniform growth of GaN on AlN templated (111)Si substrate by HVPE

Abstract

Uniform growth of thick GaN was attempted on an AlN templated (111) silicon substrate by hydride vapor phase epitaxy(HVPE). The results were very sensitive to the thickness of the AlN layer as well as the growth temperature. If the AlN is thinner than 50 nm, the surface of the silicon substrate was partly melted during the HVPE growth. If the AlN was thicker than 50 nm, the melting of the silicon surface was drastically suppressed. Uniform growth without degradation of the Si substrate was achieved at 1000 °C with a thick AlN template layer.

The influence of the Al pre-deposition on the properties of AlN buffer layer and GaN layer grown on Si (111) substrate

“…The high-density crack network could be found in samples D, some melt-back etching patterns also appeared in this sample, as shown in Fig. 4(D) indicated by arrows.Melt-back etching patterns were mainly caused by the Ga[20].…”

HVPE growth of semi-polar (112¯2)GaN on GaN template (113)Si substrate

“…It was shown that the AlN layer thicker than 200 nm is effective to prevent the melt-back-etching phenomenon. But, because of the large lattice mismatch between GaN, AlN and Si, if the thickness is more than 200 nm, cracking in the grown layer often takes place to limit the improvement [7]. An AlN/GaN multi-layer might improve the results as in the case of MOVPE [8].…”

“…In order to improve the crystalline quality, growth is undertaken at temperatures higher than 1000 1C. The HVPE growth of (0 0 0 1) GaN on (111) Si substrate was also demonstrated, where the authors pointed out the occurrence of the melt-back etching phenomena [7]. In order to suppress the reaction at the hetero-interface, insertion of an AlN intermediate layer was undertaken.…”

“…This phenomenon gives poor surface morphology to the grown layer and occasionally produces a void at the heterointerface. Because of the latter fact, it is called 'melt-back-etching' [7]. The phenomenon is more probable at high growth temperatures around 1000 1C.…”

HVPE growth of a ‐plane GaN on a GaN template (110)Si substrate

“…It is initiated by the formation of a Ga-Si solution at the heterointerface and it is called 'melt back etching' [10]. This reaction is more probable at process temperature higher than 1000 ο C. Therefore, the suppression of the melt back etching has been the issue to get a thick GaN on Si substrate.…”