HCl Flow-Induced Phase Change of α-, β-, and ε-Ga2O3 Films Grown by MOCVD

• DOI: 10.1021/acs.cgd.7b01791
• Publication Date: 2018-03-06T20:01:01Z
• Authors: Haiding Sun; Kuang-Hui Li; C. G. Torres Cast...; Serdal Okur; Gary S. Tompa; Tom Salagaj; Sergei Lopatin; Alessandro Genovese; Xiaohang Li
• Keywords: 0103 physical sciences; 01 natural sciences

Precise control of the heteroepitaxy on a low-cost foreign substrate is often key to drive success fabricating semiconductor devices in scale when large native not available. Here, we successfully synthesized three different phases Ga2O3 (α, β, and ε) films c-plane sapphire by only tuning flow rate HCl along with other precursors an MOCVD reactor. A 3-fold increase growth pure β-Ga2O3 was achieved introducing 5 sccm flow. With continuously increased flow, mixture β- ε-Ga2O3 observed, until film transformed completely smooth surface highest (∼1 μm/h) at 30 sccm. At 60 sccm, found that tended have α- dominant α-Ga2O3, while dropped significantly (∼0.4 μm/h). The became rough as result since much higher than α-Ga2O3. In this HCl-enhanced mode, Cl impurity concentration almost identical among investigated samples. On basis our density functional theory calculation, relative energy between β-, ε-, α-Ga2O3 smaller, thus inducing phase change increasing Thus, it plausible acted catalyst during transformation process. Furthermore, revealed microstructure epitaxial relationship substrates. Our approach paves way achieving highly controllable for device applications.