An epitaxial lift‐off (ELO) process for GaN materials has been demonstrated using bandgap‐selective photoenhanced wet etching of an InGaN release layer. This process has been applied to GaN layers grown on sapphire as well as native GaN substrates using a perforation technique to scale the process up to wafers of arbitrary size. The process has the advantage of leveraging conventional MOCVD growth to form the release layer, with minimal degradation of films grown on top of the release layer. The ELO process is non‐destructive and can enable cost reduction through reuse of the native GaN substrate after ELO. The GaN films have been characterized before and after ELO using AFM, SEM, XRD, TEM and by fabricating Schottky barrier diodes. The performance of Schottky diodes fabricated on GaN‐on‐sapphire structures was found to improve after ELO. Potential applications for this technology include GaN power and optoelectronic devices as well as flexible electronics. Shown is a 5‐micron‐thick GaN epitaxial film released from a 4‐inch sapphire substrate using perforations on a 1‐mm pitch. The yellow luminescence of the nitrogen face of the released film is visible under ultraviolet illumination.

Carbon, a compensator in GaN, is an inherent part of the organometallic vapor phase epitaxy (OMVPE) environment due to the use of organometallic sources. In this study, the impact of growth conditions are explored on the incorporation of carbon in GaN prepared via OMVPE on pseudo-bulk GaN wafers (in several cases, identical growths were performed on GaN-on-Al2O3 templates for comparison purposes). Growth conditions with different growth efficiencies but identical ammonia molar flows, when normalized for growth rate, resulted in identical carbon incorporation. It is concluded that only trimethylgallium which contributes to growth of the GaN layer contributes to carbon incorporation. Carbon incorporation was found to decrease proportionally with increasing ammonia molar flow, when normalized for growth rate. Ammonia molar flow divided by growth rate is proposed as a reactor independent predictor of carbon incorporation as opposed to the often-reported input V/III ratio. A low carbon concentration of 7.3 × 1014 atoms/cm3 (prepared at a growth rate of 0.57 µm/h) was obtained by optimizing growth conditions for GaN grown on pseudo-bulk GaN substrates.

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The current versus voltage (I-V) characteristics of a Ni/GaN Schottky diode are measured from 50 to 400 K and the temperature dependence of the extracted barrier heights and ideality factors is described as a consequence of lateral inhomogeneity at the metal-semiconductor (M-S) interface. It is shown that by invoking a modified log-normal distribution of barrier heights at the M-S interface, the extracted barrier height temperature dependence can be well explained. Further, it is shown that this approach can describe the voltage dependence of the lateral barrier distribution revealing that for effective barrier height values calculated at increasingly higher voltages, the distribution begins to converge on a single value of 0.77 eV. This value is in good agreement with the flat-band barrier height of 0.77±0.02 eV extracted from capacitancevoltage (C-V) measurements on the same device. The same procedure is used to describe the parallel conduction path apparent at low temperatures, revealing its behavior is indicative of an additional Schottky region with an increased density of low barriers which are more heavily perturbed by external bias. Finally, the model is successfully applied to previously published work on various Schottky diodes structures.

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