Stability investigation of cubic GaN films grown by metalorganic chemical vapor deposition on GaAs (001)

Abstract

The thermal stability of cubic-phase GaN (c-GaN) films are investigated by photoluminescence (PL) and Raman scattering spectroscopy. C-GaN films are grown on GaAs (001) substrates by metalorganic chemical vapor deposition. PL measurements show that the near-band-edge emissions in the as-grown GaN layers and thermally treated samples are mainly from c-GaN. No degradation of the optical qualities is observed after thermal annealing. Raman scattering spectroscopy shows that the intensity of the E2 peak from hexagonal GaN grains increases with annealing temperature for the samples with poor crystal quality, while thermal annealing up to 1000 °C has no obvious effect on the samples with high crystal quality.

Depth-dependent investigation of defects and impurity doping in GaN/sapphire using scanning electron microscopy and cathodoluminescence spectroscopy

“…42 Similar phenomena were also observed in cubic GaN. 43 The high defect density may be responsible for the high doping density since O can probably diffuse more rapidly in highly defective regions.…”

Growth of Single‐Crystalline Cubic GaN Nanotubes with Rectangular Cross‐Sections

“…In this process, no catalyst and no templates were used, and the growth mechanism of the c-GaN nanotubes might be markedly different from that of the templated ªepitaxial castingº during the growth of h-GaN nanotubes. [9] As depicted schematically in Figure 5, we postulate that the nucleation and growth of these c-GaN nanotubes occurs in three steps: i) As-formed Ga 2 O vapor reacts with NH 3 gas, forming GaN nanometer-sized nuclei in the flowing NH 3 and N 2 ; ii) The GaN nuclei are transported by the carrier gases of the flowing NH 3 and N 2 to a lower-temperature zone of the induction furnace. The processing conditions, such as the temperature distribution along the axial direction of the furnace, the carrier gas flow rate, the pressure inside the furnace, the gallium oxide species, and the reductive atmosphere (owing to the carbon material of the used crucible and induction furnace), and so on, will mainly dominate the dimensions, distribution, and concentration (in the flowing NH 3 and N 2 ) of the GaN nuclei.…”

“…[3,4] Since c-GaN has a lower energy bandgap than h-GaN, [5] it is easier to reach the blue and green regions when indium is incorporated in it. [3] c-GaN shows very high p-type conductivities. The optical gain in c-GaN quantum wells might be higher than that in h-GaN quantum wells.…”

“…[3] For example, epitaxially grown c-GaN films were used in the production of cleaved laser cavities. [3,4] Since c-GaN has a lower energy bandgap than h-GaN, [5] it is easier to reach the blue and green regions when indium is incorporated in it. [3] c-GaN shows very high p-type conductivities.…”

Hexagonal-to-cubic phase transformation in GaN nanowires by Ga+ implantation

“…'Redshift' of peak corresponding to E g is also reported for GaN sample with mixed cubic and hexagonal phases. 27,30 Near stoichiometric cubic phase is observed (Figure 4a Nevertheless, the formation of c-GaN NWs, with its various technological advantages over h-GaN, will be useful for futuristic device applications. …”