Properties of the state of the art of bulk III–V nitride substrates and homoepitaxial layers

Abstract

The technological importance of III-V nitride semiconductors relies on their variety of applications, which cover optical, optoelectronic and electronic devices capable of operating under extreme values of current, voltage and temperature. The major roadblock for full realization of the potential of nitride semiconductors is still the availability of affordable large-area and high-quality native substrates with controlled electrical properties. Despite the impressive accomplishments recently achieved by techniques such as hydride vapour phase epitaxy and ammonothermal for GaN and sublimation for AlN, much more must be attained before establishing a bulk growth technique of choice to grow these materials. A brief review of the structural, optical and electronic properties of the state of the art of bulk and thick-film (quasi-bulk) nitride substrates and homoepitaxial films is presented, and a few device applications are also highlighted.

GaN boules grown by high rate HVPE

“…5) taken from a cleaved edge near the backside, the middle, and near the surface did not show remarkable shifts of the excitonic emission positions. The luminescence properties of the GaN grown under our conditions are similar to those used as benchmark [22].…”

“…5 was recorded from a 2.6 mm thick GaN layer. The spectrum is dominated by emission lines from excitons which were assigned according to [21,22] as the ground state of the free exciton A (FX A ), the states of exciton A bound to an acceptor A°X A , to the donor oxygen O°X A , to the donor silicon Si°X A , the free exciton B (FX B ), and states assumed to be due to exciton B bound to donors (D°X B ). Note that two-electron satellite emissions, 1LO-, 2LO-, 3 LO-replica, a weak green band emission (GB) at 2.43 eV, and very weak yellow band emission (YB) at 2.25 eV were observed for energies below 3.46 eV (not www.pss-c.com…”

Review of using gallium nitride for ionizing radiation detection

“…[47][48][49][50][51][52] A brief review is given here with the focus on GaN's properties that are most relevant to radiation detection, though these properties are also important for other applications. Due to the lack of a native substrate, GaN is mostly grown on foreign substrates, such as AlN, 53 Si, 54 sapphire, 55 and SiC.…”

Development of 2" AlN Substrates Using SiC Seeds

“…The uniqueness of HVPE is the applicability of this method to both growth of thick substrates and epitaxial heterostructures due to an extremely wide range of growth rates (1 -150 µm/hour), the low cost compared to the MOCVD, an ability to grow the heavily doped p-layers, an absence of the carbon contamination. At present, however, the freestanding AlN films grown by HVPE are of inferior crystalline quality: the typical value of the x-ray rocking curve Full Width at Half Maximum (FWHM) is at least an order of magnitude larger than that of AlN substrate cut out from bulk AlN boule (Cai et al, 2010;Freitas, 2010); the self-separated thick (85 µm) AlN films grown recently by the three-step modification of HVPE that include the formation of numerous voids at the interface between an AlN layer and the sapphire substrate has the dislocation density on order of 10 9 cm −2 (Kumagai et al, 2008); the sublimation-grown bulk AlN crystals usually are transparent while the HVPE-grown ones are opaque (Cai et al, 2010), Tabl. 37.16.…”

“…Thus the use of this term for the process in question is not strictly correct: AlN does not sublime but rather decomposes. 12 Evidently, the source of the problem is the nitrogen pressure over GaN surface that is six orders of magnitude higher than that over AlN (Freitas, 2010). The gallium vapour is generated either from the molten gallium or by the thermal decomposition of the GaN powder (Waldrip, 2007).…”