H trapping at the metastable cation vacancy in alpha-Ga2O3 and alpha-Al2O3

alpha-Ga2O3 has the corundum structure analogous to that of alpha-Al2O3. The bandgap energy of alpha-Ga2O3 is 5.3 eV and is greater than that of beta-Ga2O3, making the alpha-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 alpha-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 (V-Ga), similar to the case of H trapped by an Al vacancy (V-Al) in alpha-Al2O3. The isolated V-Ga and V-Al defects in alpha-Ga2O3 and alpha-Al2O3 are found by theory to have a "shifted " vacancy-interstitial-vacancy equilibrium configuration, similar to V-Ga in beta-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 alpha-Ga2O3 and alpha-Al2O3. Published under an exclusive license by AIP Publishing.