Growth of high-quality GaN by halogen-free vapor phase epitaxy

Abstract

We report the electrical and optical properties of gallium nitride grown by halogen-free vapor phase epitaxy (HF-VPE). The electron mobility of the HF-VPE-GaN layers was found to be comparable to or better than the GaN layers obtained using MOCVD. The positron annihilation spectroscopy analyses revealed that the density of the electroneutral or negatively charged vacancy-type defects in the HF-VPE-GaN layers was below the detection limit (≤1015 cm−3), equivalent to that of a defect-free hydride vapor phase epitaxy (HVPE)-GaN reference sample. Our study shows that the HF-VPE technique can be employed to achieve high-quality and cost-effective bulk crystal and epitaxial layer growth for GaN devices.

Self-assembled single-crystal bimodal porous GaN exhibiting a petal effect: application as a sensing platform and substrate for optical devices

“…2(a) shows the relationship between the Si concentration and free-electron concentration n for porous GaN and the previously reported flat GaN grown by HF-VPE. 25 The porous GaN data presented in Fig. 2(a) and (b) were calculated assuming that porous GaN has 50% porosity.…”

“…The porous GaN samples were fabricated through HF-VPE 22,25–30 on MOCVD GaN on sapphire substrate (MO template) (ESI†). 22,25–30 The bimodal meso/macro porous structure was a self-assembled structure generated by the anti-surfactant effect of B during GaN growth.…”

“…The porous GaN samples were fabricated through HF-VPE 22,[25][26][27][28][29][30] on MOCVD GaN on sapphire substrate (MO template) (ESI †). 22,[25][26][27][28][29][30] The bimodal meso/macro porous structure was a self-assembled structure generated by the anti-surfactant effect of B during GaN growth. 22,26 Details regarding the growth conguration and conditions have been reported elsewhere.…”

Temperature Characterization of Unipolar-Doped Electroluminescence in Vertical GaN/AlN Heterostructures

“…The optical transition at ∼4.2 K is most likely B-exciton emission, being associated with the interband transition Γ V 7 (upper valence band)→ Γ C 7 in bulk GaN. At T = 30 K, the emission is likely A-exciton emission but it may be mixed with or even dominated by shallow-donor-bound exciton emission as the temperature is below ≈ 50 K according to [7,[19][20][21][22][23]. Differentiation of the two, free or shallow-donor-bound, requires reflection experiments as only the free (or A type) excitons is strong in reflectance (e.g., [14][15][16]22]), this is beyond the scope of this paper and may not be feasible for the electroluminescence phenomenon we are investigating.…”

Origins of Electrical Compensation in Si‐Doped HVPE GaN

“…Concentrations of Ga vacancies in undoped HVPE grown GaN are generally found to be below , which is the detection limit of positron annihilation spectroscopies. [ 5–7 ] Ga vacancies and related defects are formed at higher concentrations by intentionally increasing the O content in the material, reaching up to if the O concentrations exceed . [ 3,8 ] The Ga vacancies act as compensating acceptors for n‐type doping caused by the O impurities, but their concentrations remain very low compared to the O content and hence they are insignificant from the point of view of overall compensation.…”