X-ray diffraction analysis of cubic zincblende III-nitrides

Abstract

Solving the green gap problem is a key challenge for the development of future LED-based light systems. A promising approach to achieve higher LED efficiencies in the green spectral region is the growth of III-nitrides in the cubic zincblende phase. However, the metastability of zincblende GaN along with the crystal growth process often lead to a phase mixture with the wurtzite phase, high mosaicity, high densities of extended defects and point defects, and strain, which can all impair the performance of light emitting devices. X-ray diffraction (XRD) is the main characterization technique to analyze these device-relevant structural properties, as it is very cheap in comparison to other techniques and enables fast feedback times. In this review, we will describe and apply various XRD techniques to identify the phase purity in predominantly zincblende GaN thin films, to analyze their mosaicity, strain state, and wafer curvature. The different techniques will be illustrated on samples grown by metalorganic vapor phase epitaxy on pieces of 4″ SiC/Si wafers. We will discuss possible issues, which may arise during experimentation, and provide a critical view on the common theories.

Investigation of MOVPE-grown zincblende GaN nucleation layers on 3C-SiC/Si substrates

“…The substrates consisted of ~ 3 µm thick layer of CMP-polished 3C-SiC grown on a 1000 m thick Si(001) wafer with either a 4° or 2° miscut towards the [110] inplane direction. 3C-SiC/Si substrates have the advantage of a small lattice mismatch with zb-GaN of 3.4% at room temperature [25] and being available in large diameters of up to 150 mm at present. Trimethylgallium (TMG) and ammonia (NH3) were used as Ga and N sources, and hydrogen was used as the carrier gas.…”

Effective bond-orbital model of III-nitride wurtzite structures based on modified interaction parameters of zinc-blende structures

“…[2] and Ref. [27]. The other input parameters including heavy-hole band energies at X and L points, E HH (L) and E HH (X), the light-hole band energy at X point, E LH (X), and the transition energies at X and L points,…”

Effect of growth temperature and V/III-ratio on the surface morphology of MOVPE-grown cubic zincblende GaN

“…A few groups reported the growth of zb-GaN on GaAs (001) substrates by molecular beam epitaxy (MBE) [18][19][20] and metalorganic vapour phase epitaxy (MOVPE) 21,22 , but the high thermal stability of 3C-SiC substrates is preferable because of the relatively high temperatures required for GaN growth [23][24][25] . Moreover, 3C-SiC has a relatively small lattice mismatch of 3.4 % with respect to zb-GaN 26 , and the current availability of high-quality 3C-SiC/Si(001) substrates of up to 150 mm in diameter presents a promising choice of substrate for zb-GaN films. A comparison of the MOVPE conditions studied by the different groups [23][24][25] indicates that the highest quality films were grown using a two-step growth procedure similar to that normally used on (0001) sapphire, which included a thin low-temperature GaN nucleation layer, followed by high temperature epilayer growth.…”