不同退火条件对PEALD制备的Ga2O3薄膜特性的影响

利用等离子增强原子层沉积技术(PEALD)在c面蓝宝石衬底上制备了氧化镓(Ga₂O₃)薄膜,研究了退火气氛(v(N₂)∶v(O₂)=1∶1(体积比)、空气和N₂)及退火时间对Ga₂O₃薄膜晶体结构、表面形貌和光学性质的影响。研究结果表明,退火前的氧化镓处于亚稳态,不同退火气氛下退火后晶体结构发生明显改变,而且退火气氛中N₂比例增加有利于Ga₂O₃重结晶。在N₂气氛下退火达到30 min,薄膜结构已由亚稳态转变成择优取向的β-Ga₂O₃。而且表面形貌分析表明,退火30 min后表面形貌开始趋于稳定,表面晶粒密度不再增加。另外实验样品在 400~800 nm的平均透射率几乎是100%,且光吸收边陡峭。采用N₂气氛退火,对于富氧环境下沉积的Ga₂O₃更利于薄膜表面原子迁移,以及择优取向Ga₂O₃重结晶。

Effects of Different Annealing Conditions on the Characteristics of Ga2O3 Thin Films Prepared by PEALD

Gallium oxide (Ga₂O₃) thin films were prepared on c-plane sapphire substrates by plasma enhanced atomic layer deposition (PEALD). The effects of annealing atmosphere (v(N₂)∶v(O₂)=1∶1 (volume ratio), Air and N₂) and annealing time on the crystal structure, surface morphology and optical properties of Ga₂O₃ films were studied. The research results indicate that gallium oxide is in metastable state before annealing, and the crystal structure changes significantly after annealing in different annealing atmospheres, and the increase in the proportion of N₂ in annealing atmosphere is beneficial to the recrystallization of Ga₂O₃. Furthermore, the effect of annealing time was further studied under N₂ atmosphere, and the results show that the structure of the thin film changes from metastable state to β-Ga₂O₃ with good single orientation after annealing for 30 min in N₂ atmosphere. And the surface morphology analysis show that the surface morphology begins to stabilize after annealing for 30 min, and the surface grain density no longer increases. In addition, the average transmittance of the sample in the range of 400 nm to 800 nm is almost 100%, and the light absorption edge is steep. Annealing in N₂ atmosphere is more conducive to the migration of atoms on the surface of the film for Ga₂O₃ deposited in an oxygen-rich environment, and Ga₂O₃ recrystallization is preferred.