Growth of GaN quasi‐substrates by hydride vapor phase epitaxy

Abstract

To grow high quality GaN heteroepitaxially is a difficult task due to the lattice mismatch and differences in thermal expansion coefficients between the films and the foreign substrates. A large number of structural defects form in the films, which lateron may limit the performance in the devices. Hydride vapor phase epitaxy is a high-growth-rate technique which has the potential to faciliate large area, low defect density "GaN quasi-substrates" for subsequent growth by MOCVD or MBE. We report on a flow modulated growth process which includes a nitridation of the sapphire substrate and the growth of high temperature buffer layers. The strucutral and optical properties of the films are presented and compared at different stages of the growth process.

Vertical transport in group III‐nitride heterostructures and application in AlN/GaN resonant tunneling diodes

“…Consequently, the development of growth techniques for the fabrication of low dislocation density templates by metalorganic chemical vapour phase epitaxy (MOVPE) and epitaxial lateral overgrowth (ELOG) [42] as well as dislocation reduction in MBE grown layers [43,44] are subject of intense research and a prerequisite for the realization of quantum tunneling devices. In reference [27], an improved MBE growth technique based on the insertion of high-temperature-grown AlN intermediate layers into the GaN buffer layer by alternate supply of nitrogen and aluminum reduced the propagation of dislocations in heterostructures grown on MOCVD templates to 8 × 10 9 cm -2 .…”

Surface chemistry and transport effects in GaN hydride vapor phase epitaxy

“…This limitation would have been avoided by using the substrates made of bulk GaN or AlN, however, the growth technologies of these materials are still far from the production level. An alternative approach is based on hydride vapour phase epitaxy (HVPE) capable of producing thick quasi-bulk epilayers on the commercially available substrates [3][4][5][6]. This technique, which is historically the first one to grow GaN, provides relatively high growth rates, typically $50-200 mm/h, and, in combination with the epitaxial lateral overgrowth (ELOG) [7,8], reduced dislocation density of $10 6 -10 8 cm À2 .…”

III-Nitride-Based Short-Wavelength Ultraviolet Light Sources

“…Recently, there have been major developments in the production of native substrates, including GaN, AlN, and their alloys, as free-standing wafers using a variety of growth techniques (Bockowski et al, 2004;Zhang and Meyer 2003;Rojo et al, 2001;Kim et al, 1998). However, the stage has not reached where these substrates of consistently high quality and size Table 1 Summary of the major developments that took place during the development of III-nitride-based UV emitters…”