Annealing temperature controlled crystallization mechanism and properties of gallium oxide film in forming gas atmosphere
Chen Wang, Shiwei Li, Wei‐Hang Fan, Yuchao Zhang, Haijun Lin, Xiaoying Zhang, Shui‐Yang Lien, Wen‐Zhang Zhu, Dong‐Sing Wuu
Abstract
Abstract Gallium oxide (Ga 2 O 3 ) films had been fabricated on Al 2 O 3 (0001) substrate by employing pulsed laser deposition (PLD) and annealed at different temperatures under forming gas (FG) atmosphere (95% N 2 + 5% H 2 ). The influence of annealing temperature on the structural, optical, chemical composition, and surface morphological properties of the Ga 2 O 3 thin films was investigated comprehensively. The annealing processes with hydrogen gas play a crucial role in the characteristics of Ga 2 O 3 thin films. A crystallization mechanism of Ga 2 O 3 films controlled by annealing temperature has been proposed firstly and analyzed systematically, which contains three kinds of competitive mechanism, namely the thermal enhanced crystallization, the enhanced H 2 dissociative adsorption on Ga 2 O 3 surfaces, and the high‐temperature decomposition of Ga 2 O 3 . Both Ga + and Ga 3+ oxidation valence states were presented in all samples, which indicated lattice oxygen deficiency in Ga 2 O 3 films. The variation of the non‐lattice oxygen proportion of Ga 2 O 3 films related to the crystallization mechanism firstly increased and then decreased with the increase of annealing temperature. The detailed crystallization mechanism of PLD‐Ga 2 O 3 films annealed in FG offers a guideline and references for the further fabrication of high‐quality Ga 2 O 3 films and their applications in high‐performance devices.