氧分压对磁控溅射β-Ga2O3薄膜结构及光学特性的影响

Effect of Oxygen Partial Pressure During Sputtering on Structural and Optical Properties of β-Ga2O3 Thin Films

摘要:

通过磁控溅射沉积以及高温热退火处理,在5.08cm(2inch)c-plane 蓝宝石异质衬底上制备出单晶β-Ga₂O₃薄膜,研究了溅射气氛中氧分压对β-Ga₂O₃薄膜的晶体结构以及光学特性的影响。通过调控氧分压,获得了具有{-201}晶面族X射线衍射峰的β-Ga₂O₃薄膜,其最大晶粒尺寸达到138nm,在300~800nm波段透射率大于80%,最大光学带隙达5.12eV。最优的薄膜表面粗糙度达0.401nm,800nm波长处折射率为1.94。实验结果表明,降低氧分压有利于溅射粒子动能增大、数量增多,从而提升β-Ga₂O₃薄膜结晶质量、增加薄膜透射率和光学带隙；适当提高氧分压则有利于改善薄膜表面平整度,并提高致密度。

Abstract:

Single crystalline β-Ga₂O₃ thin films were deposited on 5.08nm (2inch) c-plane sapphire substrates by magnetron sputtering and then were annealed. The effects of oxygen partial pressure during sputtering on the structural and optical properties of films were systematically investigated. In this study, a single crystalline β-Ga₂O₃ thin film with a crystalline size of 138nm, a transparency larger than 80% and a wide bandgap of 5.12eV, has been accomplished by modifying oxygen partial pressure. And a β-Ga₂O₃ thin film has been improved with a roughness as low as 0.401nm and a refractive index of 1.94 at 800nm. The results show that, reducing oxygen partial pressure during sputtering is helpful to improve crystalline quality and increase the transparency and optical band gap by increasing the numbers of sputtered particles as well as their kinetic energy. However, increasing oxygen partial pressure is beneficial to improve the film surface evenness and density.