H trapping at the metastable cation vacancy in α-Ga2O3 and α-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.

Automated summary

alpha-Ga2O3, similar to alpha-Al2O3 in structure, has a larger bandgap energy, making it attractive for devices requiring wider bandgaps. Studies on O-H and O-D centers in alpha-Ga2O3 implanted with H+ and D+ ions, along with complementary theory, suggest that H complexes with Ga vacancies, similar to H trapped by Al vacancies in alpha-Al2O3. Theoretical analysis reveals that V-Ga and V-Al defects in alpha-Ga2O3 and alpha-Al2O3 have shifted equilibrium configurations, similar to V-Ga in beta-Ga2O3. However, the addition of H results in the lowest energy state being a complex with H trapped at an unshifted vacancy in both alpha-Ga2O3 and alpha-Al2O3.