Modified high temperature vapor phase epitaxy for growth of GaN films

Abstract

The high temperature vapor phase epitaxy (HTVPE) uses ammonia and thermally evaporated, elemental gallium as precursors for the growth of GaN films. This paper investigates the HTVPE using numerical modeling of the gallium vapor transport and systematical growth experiments. The presented growth setup allows a flexible control of the growth process and variation of growth parameters in a wide range. Based on simulation results, the impact of the gallium melt temperature, the gas flow in the reactor and the reactor pressure on the gallium vapor transport is studied in detail. Experimental growth rates as function of the reactor pressure and the melt temperature are compared with the numerical simulation. The influence of hydrogen in the carrier gas on the properties of the HTVPE GaN layers is discussed.

Defect-rich GaN interlayer facilitating the annihilation of threading dislocations in polar GaN crystals grown on (0001)-oriented sapphire substrates

“…37 The HTVPE technique offers high flexibility of the deposition process through the variation of the flow of precursors, the source and substrate temperatures, the reactor pressure, and the growth rate. [38][39][40] To reduce the TD density, we deposited a defect-rich GaN interlayer in which the TDs interact with other microstructure defects. This concept of the defect engineering employs a variation of the deposition parameters that results in the emergence of ( partial) stacking faults (SFs), 40,41 voids, 41 and occasionally inverse domain boundaries.…”

Influence of Ammonia Flow on Microstructural Properties of Polar GaN Layers Grown by HTVPE on Sapphire Substrates

“…Densities of screw and edge TDs as well as the total dislocation density ( + ) that are depicted using black squares, red circles and blue triangles, respectively, were calculated from the reciprocal space maps using the Monte Carlo algorithm . Green star corresponds to the density of screw TDs obtained from the modified Williamson‐Hall plot . For other samples, the modified Williamson‐Hall method revealed the similar density of screw TDs as the Monte Carlo algorithm.…”

“…The GaN layers were deposited using a similar growth setup like in ref. []. First, 50 nm thick nucleation GaN layers were deposited on (001)‐oriented sapphire substrates at a temperature of 500 °C and at a total pressure of 1 bar.…”

“…Except conventional growth methods, modified high‐temperature vapor phase epitaxy (HTVPE) that uses thermally evaporated gallium and ammonia as precursors seems to be a suitable technique for the GaN deposition. This growth technique exhibits large application potential due to its high degree of flexibility . Besides, it can be used to investigate the GaN growth in a broad range of the deposition parameters and to stimulate the growth of specific microstructure features and defects that may facilitate the annihilation of threading dislocations.…”

“…In this work, we describe the microstructure of (001)‐oriented GaN thin films grown directly on (001)‐oriented sapphire substrates using a low‐temperature (LT) nucleation procedure . The central microstructure parameters are the density of TDs and residual stress that were determined using high‐resolution X‐ray diffraction (HRXRD) and micro‐Raman spectroscopy.…”