Ti Alloyed α-Ga₂O₃: Route towards Wide Band Gap Engineering

The suitability of Ti as a band gap modifier for α-Ga₂O₃ was investigated, taking advantage of the isostructural α phases and high band gap difference between Ti₂O₃ and Ga₂O₃. Films of (Ti,Ga)₂O₃ were synthesized by atomic layer deposition on sapphire substrates, and characterized to determine how crystallinity and band gap vary with composition for this alloy. We report the deposition of high quality α-(Ti_xGa_1-x)₂O₃ films with x = 3.7%. For greater compositions the crystalline quality of the films degrades rapidly, where the corundum phase is maintained in films up to x = 5.3%, and films containing greater Ti fractions being amorphous. Over the range of achieved corundum phase films, that is 0% ≤ x ≤ 5.3%, the band gap energy varies by ∼270 meV. The ability to maintain a crystalline phase at low fractions of Ti, accompanied by a modification in band gap, shows promising prospects for band gap engineering and the development of wavelength specific solar-blind photodetectors based on α-Ga₂O₃.