Growth of epitaxial AlxGa1−xN films by pulsed laser deposition

Abstract

Epitaxial AlxGa1−xN films have been grown on c-cut sapphire substrates at 800 °C and 10−2 Torr N2 by pulsed laser deposition (PLD) using a KrF laser. Throughout the composition range from x=0 to 0.6, the films show epitaxial patterns in reflection high-energy electron diffraction, in agreement with the results from x-ray diffraction. The lattice constants of the films vary linearly with x. The composition dependence of the band gaps of the films deviates from linearity and bows downward. This letter reports the application of PLD to controlling the lattice constant and band gap by varying the proportion of AlN and GaN in the target mixture.

LP MOVPE growth and characterization of high Al content AlxGa1−xN epilayers

“…The same shape was observed for Al xGa 1Àx N films with different Al composition. With increasing the Al concentration, the AlGaN peak position shifts towards higher angles showing a decrease of the lattice constant c. Huang et al [19] have found the same behaviour for Al x Ga 1Àx N with Al content varying between 0 and 60%. The variation of the full width at half maximum (FWHM) of the Al x Ga 1Àx N films versus Al content is shown in the inset of Fig.…”

Electron Bandstructure Parameters

“…First, the early findings of an upward bowing [247,248] were generally not duplicated (with the somewhat inconclusive exception of Ref. The second class of materials, which were grown at high temperatures, generally exhibited a strong downward bowing of at least +1.3 eV [142,[253][254][255][256][257][258]. The second class of materials, which were grown at high temperatures, generally exhibited a strong downward bowing of at least +1.3 eV [142,[253][254][255][256][257][258].…”

Pulsed Laser Deposition (PLD)

“…Early attempts to grow AlGaN alloy utilized ceramic targets prepared from GaN and AlN powder mixtures [100]. Early attempts to grow AlGaN alloy utilized ceramic targets prepared from GaN and AlN powder mixtures [100].…”