Energy gap of dilute As-rich (Ref. 2) and N-rich (Ref. 12) alloys as a function of x reported in literature. The solid line is the calculated band gap of dilute alloys based on the BAC model interpolated over the entire composition range. Band gaps by VCA and by a forced quadratic fitting to the experimental gap energies using a single bowing parameter of are also shown.
The arsenic composition in films grown by LT-MBE measured by RBS/PIXE as a function of growth temperature. The Ga and fluxes with BEPs of and , respectively, were used in these MBE growths.
XRD patterns from films (a) in the N-rich regime grown at temperature from 200 to , and (b) in the As-rich regime grown at with increasing Ga flux. XRD pattern from a phase separated film grown at is also shown in (b) for comparison. The patterns are shifted vertically.
(a) A series of SAD patterns from alloys with increasing As content as a result of decreasing growth temperature from 550 to . (b) Two typical cross-sectional TEM micrographs of a crystalline and an amorphous film .
The energy dependence of the square of the absorption coefficient for layers grown at different temperatures from to .
Dependence of the optical band gap energy on the value of x for crystalline and amorphous alloys. Calculated composition dependences of the band gap of alloys based on the BAC, VCA, and using a single bowing parameter extracted from dilute alloys are also shown.
The nitrogen -edge SXE and total fluorescence yield XAS of films with different As fractions. An elastic emission peak in the threshold-excited SXE is used for energy calibration to XAS. The inset shows the magnified view of the XAS and SXE threshold regions.
Composition dependence of the CBM and the VBM energies for alloys as measured by XAS and SXE, respectively, plotted together with the BAC predicted values. The linear interpolations of CB and VB between end point compounds (GaN and GaAs) are also shown. The positions of the redox potentials with respect to the VBM of GaN are also shown.
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