Effect of high-temperature annealing on AlN thin film grown by metalorganic chemical vapor deposition

Abstract

The effect of high-temperature annealing on AlN thin film grown by metalorganic chemical vapor deposition was investigated using atomic force microscopy, Raman spectroscopy, and deep ultra-violet photoluminescence (PL) with the excitation wavelength as short as ∼ 177 nm. Annealing experiments were carried out in either N 2 or vacuum atmosphere with the annealing temperature ranging from 1200 • C to 1600 • C. It is found that surface roughness reduced and compressive strain increased with the annealing temperature increasing in both annealing atmospheres. As to optical properties, a band-edge emission peak at 6.036 eV and a very broad emission band peaking at about 4.7 eV were observed in the photoluminescence spectrum of the as-grown sample. After annealing, the intensity of the band-edge emission peak varied with the annealing temperature and atmosphere. It is also found that a much stronger emission band ranging from 2.5 eV to 4.2 eV is superimposed on the original spectra by annealing in either N 2 or vacuum atmosphere. We attribute these deep-level emission peaks to the V AL -O N complex in the AlN material.

Dislocation densities reduction in MBE-grown AlN thin films by high-temperature annealing

“…There have been several approaches to reduce these defects, one of the most promising one being the post-growth annealing. Since the last decade, the annealing of the AlN films have been studied on films grown by sputtering, 6 pulsed laser deposition (PLD) 7 , metal-organic vapor phase epitaxy (MOVPE) 8,9 and molecular beam epitaxy (MBE). [10][11][12] In particular, the AlN films grown by MBE on sapphire substrates have been annealed under N2 atmosphere at various temperatures and durations, from multiple cycles of 10 s, up to 1200 °C, 11 to recently a combination of a 30 min annealing at 1150 °C followed by 20 pulses up to 1520 °C.…”

Core–shell GaN/AlGaN nanowires grown by selective area epitaxy

“…4c, the location of these acceptor impurity levels in the forbidden gap suggests that the defects in the samples Al-40 and Al-50 are a (V III -complex) 1− . Oxygen-related defects in GaN, 52 and AlN, 53 show luminescence at 2.8 and 4.7 eV, respectively, which are located at the ends of the horizontal line indicating the (V III -complex) 1− in Fig. 4c.…”

Exciton–phonon interaction in Al 0.4 Ga 0.6 N/Al 0.53 Ga 0.47 N multiple quantum wells

“…AlGaN-based multiple quantum wells (MQWs) with high Al content have attracted intensive attention for their device applications in deep-ultraviolet (DUV) light emitting diodes (LEDs), [1][2][3] laser diodes (LDs), [4,5] and detectors. [6,7] Understanding light emission and absorption mechanisms in AlGaN MQWs is important for developing these devices. The exciton-phonon interaction, one of the intrinsic physical properties, is an important effect that appears in the optical process.…”