  In this work, bulk Czochralski-grown single crystals of 10 mol. % Al2O3
alloyed B-Ga2O3 - monoclinic 10% AGO or B-(Al0.1Ga0.9)2O3 - are obtained, which
show +0.20 eV increase in the bandgap compared with unintentionally doped
B-Ga2O3. Further, growths of 33% AGO - B-(Al0.33Ga0.67)2O3 - and 50% AGO -
B-(Al0.5Ga0.5)2O3 or B-AlGaO3 - produce polycrystalline single-phase monoclinic
material (B-AGO). All three compositions are investigated by x-ray diffraction,
Raman spectroscopy, optical absorption, and 27Al nuclear magnetic resonance
(NMR). By investigating single phase B-AGO over a large range of Al2O3
concentrations (10 - 50 mol. %), broad trends in the lattice parameter,
vibrational modes, optical bandgap, and crystallographic site preference are
determined. All lattice parameters show a linear trend with Al incorporation.
According to NMR, aluminum incorporates on both crystallographic sites of
B-Ga2O3, with a slight preference for the octahedral (GaII) site, which becomes
more disordered with increasing Al. Single crystals of 10% AGO were also
characterized by x-ray rocking curve, transmission electron microscopy, purity
(glow discharge mass spectroscopy and x-ray fluorescence), optical transmission
(200 nm - 20 um wavelengths), and resistivity. These measurements suggest that
electrical compensation by impurity acceptor doping is not the likely
explanation for high resistivity, but rather the shift of a hydrogen level from
a shallow donor to a deep acceptor due to Al alloying. .. Cont.
  This article may be downloaded for personal use only. Any other use requires
prior permission of the author and AIP Publishing. This article appeared in
Journal of Applied Physics 131 155702.
