氧气分压对磁控溅射β-Ga2O3薄膜结构及光学特性的影响

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

摘要:

本研究通过磁控溅射沉积以及高温热退火处理，在2英寸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气分压（氧气体积比=[O2]/([O2]+[Ar])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1380 ?，在300-800 nm波段透射率>80%，最大光学带隙达5.12 eV。最优的薄膜表面粗糙度达0.401 nm，800 nm波长处折射率为1.94。研究结果表明，降低氧气分压有利于溅射粒子动能增大、数量增多，从而有利于提升β-Ga2O3薄膜结晶质量、增加薄膜透射率和光学带隙。然而，适当提高氧气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 2-inch c-plane sapphire substrates by magnetron sputtering and then were annealed. The effects of oxygen partial pressure (O2 volume ratio=[O2]/([O2]+[Ar]) 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 1380 ?, a transparency larger than 80% and a wide bandgap of 5.12 eV, has been accomplished through modifying oxygen partial pressure. And a β-Ga2O3 thin film has been improved with a roughness as low as 0.401 nm and a refractive index of 1.94 at 800 nm. The results show that: reducing oxygen partial pressure during sputtering helped improve crystalline quality, increase the transparency and optical bandgap by increasing the numbers of sputtered particles as well as their kinetic energy; however, increasing oxygen partial pressure was beneficial to film smoother surface and higher density.