Rutile germanium dioxide (r-GeO2) has been identified as an ultrawide bandgap semiconductor recently, featuring a bandgap of 4.68 eV—comparable to Ga2O3—but offering bipolar dopability, higher electron mobility, higher thermal conductivity, and higher Baliga figure of merit (BFOM). These superior properties position GeO2 as a promising material for various semiconductor applications. However, the epitaxial growth of r-GeO2, particularly in its most advantageous rutile polymorph, is still at an early stage. This work explores the growth of r-GeO2 using metal-organic chemical vapor deposition (MOCVD) on an r-TiO2 (001) substrate, utilizing tetraethyl germane as the precursor. Our investigations reveal that higher growth temperatures significantly enhance crystalline quality, achieving a full width at half maximum of 0.181° at 925 °C, compared to 0.54° at 840 °C and amorphous structures at 725 °C. Additionally, we found that longer growth durations increase surface roughness due to the formation of faceted crystals. Meanwhile, adjusting the susceptor rotation speed from 300 to 170 RPM plays a crucial role in optimizing crystalline quality, effectively reducing surface roughness by approximately 15 times. This study offers a foundational guide for optimizing MOCVD growth conditions of r-GeO2 films, emphasizing the crucial need for precise control over deposition temperature and rotation speed to enhance adatom mobility and effectively minimize the boundary layer thickness.

中文翻译：

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通过 MOCVD 实现金红石型 GeO2 的外延生长


金红石型二氧化锗 （r-GeO2） 最近被确定为超宽带隙半导体，其带隙为 4.68 eV，与 Ga2O3 相当，但具有双极多分子密度、更高的电子迁移率、更高的热导率和更高的巴里加品质因数 （BFOM）。这些卓越的性能使 GeO2 成为各种半导体应用的有前途的材料。然而，r-GeO2 的外延生长，特别是其最有利的金红石多晶型物，仍处于早期阶段。这项工作利用金属有机化学气相沉积 （MOCVD） 在 r-TiO2 （001） 衬底上，利用四乙基锗作为前驱体，探索了 r-GeO2 的生长。我们的研究表明，较高的生长温度显著提高了晶体质量，在 925 °C 时实现了 0.181° 的半峰全宽，而在 840 °C 时达到 0.54°，在 725 °C 时达到无定形结构。 此外，我们发现，由于刻面晶体的形成，较长的生长持续时间会增加表面粗糙度。同时，将基座转速从 300 RPM 调整到 170 RPM 对优化晶体质量起着至关重要的作用，可有效将表面粗糙度降低约 15 倍。本研究为优化 r-GeO2 薄膜的 MOCVD 生长条件提供了基础指南，强调了精确控制沉积温度和转速以增强吸附原子迁移率并有效减小边界层厚度的关键需求。