Anisotropic And Trap-Limited Diffusion Of Hydrogen/Deuterium In Monoclinic Gallium Oxide Single Crystals

The effect of lattice anisotropy on the diffusion of hydrogen (H)/deuterium (H-2) in beta -Ga2O3 was investigated using secondary ion mass spectrometry (SIMS) and hybrid-functional calculations. Concentration-depth profiles of H-2-implanted single crystals show that H-2 can diffuse along the direction perpendicular to the (010) surface at temperatures as low as 300 degrees C, whereas diffusion along the direction perpendicular to the (-201) surface occurs only around 500 degrees C. For both directions, the evolution of the H-2 concentration-depth profiles after heat treatments can be modeled by trap-limited diffusion. Moreover, the traps can be present in the as-received crystals or created during ion implantation. Comparison of the experimentally obtained binding energy for H-2 to the trap (2.3 +/- 0.2eV) with the binding energies determined from first-principles calculations suggests that intrinsic point defects (e.g.,VGaib) or defect complexes (e.g.,VGa ( 2 ) VO ( 2 )) are excellent candidates for the trap and will play a crucial role in the diffusion of H or H-2 in beta -Ga2O3.