α-Ga2O3has the corundum structure analogous to that of α-Al2O3. The bandgap energy of α-Ga2O3is 5.3 eV and is greater than that of β-Ga2O3, making the α-phase attractive for devices that benefit from its wider bandgap. The O–H and O–D centers produced by the implantation of H+and D+into α-Ga2O3have been studied by infrared spectroscopy and complementary theory. An O–H line at 3269 cm−1is assigned to H complexed with a Ga vacancy (VGa), similar to the case of H trapped by an Al vacancy (VAl) in α-Al2O3. The isolated VGaand VAldefects in α-Ga2O3and α-Al2O3are found by theory to have a “shifted” vacancy-interstitial-vacancy equilibrium configuration, similar to VGain β-Ga2O3, which also has shifted structures. However, the addition of H causes the complex with H trapped at an unshifted vacancy to have the lowest energy in both α-Ga2O3and α-Al2O3.
While a number of O-H and O-D vibrational lines have been observed for hydrogen and deuterium in β-Ga2O3, it has been commonly reported that there is no absorption with a component of the polarization E parallel to the [010], or b, axis. This experimental result has led to O-H defect structures that involve shifted configurations of a vacancy at the tetrahedrally coordinated Ga(1) site [VGa(1)] and have ruled out structures that involve a vacancy at the octahedrally coordinated Ga(2) site [VGa(2)], because these structures are predicted to show absorption for E//[010]. In this Letter, weak O-D lines at 2475 and 2493 cm−1 with a component of their polarization with E//[010] are reported for β-Ga2O3 that had been annealed in a D2 ambient. O-D defect structures involving an unshifted VGa(2) are proposed for these centers. An estimate is made that the concentration of VGa(2) in a Czochralski-grown sample is 2–3 orders of magnitude lower than that of VGa(1) from the intensities of the IR absorption lines.
more » « less- Award ID(s):
- 1856662
- NSF-PAR ID:
- 10440621
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 122
- Issue:
- 6
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The ion implantation of H+and D+into Ga2O3produces several O–H and O–D centers that have been investigated by vibrational spectroscopy. These defects include the dominant VGa(1)-2H and VGa(1)-2D centers studied previously along with additional defects that can be converted into this structure by thermal annealing. The polarization dependence of the spectra has also been analyzed to determine the directions of the transition moments of the defects and to provide information about defect structure. Our experimental results show that the implantation of H+(or D+) into Ga2O3produces two classes of defects with different polarization properties. Theory finds that these O–H (or O–D) centers are based on two shifted configurations of a Ga(1) vacancy that trap H (or D) atom(s). The interaction of VGa(1)-nD centers with other defects in the implanted samples has also been investigated to help explain the number of O–D lines seen and their reactions upon annealing. Hydrogenated divacancy VGa(1)-VOcenters have been considered as an example.
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α-Ga2O3 has the corundum structure analogous to that of α-Al2O3. The bandgap energy of α-Ga2O3 is 5.3 eV and is greater than that of β-Ga2O3, making the α-phase attractive for devices that benefit from its wider bandgap. The O-H and O-D centers produced by the implantation of H+ and D+ into α-Ga2O3 have been studied by infrared spectroscopy and complementary theory. An O-H line at 3269 cm-1 is assigned to H complexed with a Ga vacancy (VGa), similar to the case of H trapped by an Al vacancy (VAl) in α-Al2O3. The isolated VGa and VAl defects in α-Ga2O3 and α-Al2O3 are found by theory to have a “shifted” vacancy-interstitial-vacancy equlibrium configuration, similar to VGa in β-Ga2O3 which also has shifted structures. However, the addition of H causes the complex with H trapped at an unshifted vacancy to have the lowest energy in both α-Ga2O3 and α-Al2O3.more » « less
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