High crystalline quality homoepitaxial Si-doped β -Ga 2 O 3 (010) layers with reduced structural anisotropy grown by hot-wall MOCVD

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2024, Vol.42 (2)
• Main Authors: Gogova-Petrova, Daniela, Tran, Dat, Stanishev, Vallery, Jokubavicius, Valdas, Vines, L., Schubert, M., Yakimova, Rositsa, Paskov, Plamen, Darakchieva, Vanya
• Format: Article
• Language: English
• ISSN: 1520-8559; 0734-2101
• DOI: 10.1116/6.0003424

A new growth approach, based on the hot-wall metalorganic chemical vapor deposition concept, is developed for high-quality homoepitaxial growth of Si-doped single-crystalline beta-Ga2O3 layers on (010)-oriented native substrates. Substrate annealing in argon atmosphere for 1 min at temperatures below 600 degrees C is proposed for the formation of epi-ready surfaces as a cost-effective alternative to the traditionally employed annealing process in oxygen-containing atmosphere with a time duration of 1 h at about 1000 degrees C. It is shown that the on-axis rocking curve widths exhibit anisotropic dependence on the azimuth angle with minima for in-plane direction parallel to the [001] and maximum for the [100] for both substrate and layer. The homoepitaxial layers are demonstrated to have excellent structural properties with a beta-Ga2O3(020) rocking curve full-widths at half-maximum as low as 11 arc sec, which is lower than the corresponding one for the substrates (19 arc sec), even for highly Si-doped (low 1019 cm -3 range) layers. Furthermore, the structural anisotropy in the layer is substantially reduced with respect to the substrate. Very smooth surface morphology of the epilayers with a root mean square roughness value of 0.6 nm over a 5 x 5 mu m(2) area is achieved along with a high electron mobility of 69 cm 2 V -1 s -1 at a free carrier concentration n = 1.9 x 10(19) cm -3. These values compare well with state-of-the-art parameters reported in the literature for beta-Ga2O3(010) homoepitaxial layers with respective Si doping levels. Thermal conductivity of 17.4 Wm(-1)K(-1) is determined along the [010] direction for the homoepitaxial layers at 300 K, which approaches the respective value of bulk crystal (20.6 Wm(-1)K(-1)). This result is explained by a weak boundary effect and a low dislocation density in the homoepitaxial layers.