Bandgap modulation and electrical characteristics of (AlxGa1−x)2O3/4H-SiC thin film heterostructures

• Published in: Thin solid films Vol. 754; p. 139276
• Main Authors: Lee, Hee-Jae, Shin, Myeong-Cheol, Moon, Soo-Young, Byun, Dong-Wook, Kim, Min-Yeong, Lee, Hyung-Jin, Lee, Geon-Hee, Jung, Seung-Woo, Schweitz, Michael A., Park, JoonHui, Rim, Youseung, Koo, Sang-Mo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.07.2022
• Subjects: Aluminum gallium oxide; Bandgap engineering; Gallium oxide; Heterostructure; Wide bandgap; Heterostructure; Aluminum gallium oxide; Bandgap engineering; Wide bandgap; Gallium oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2022.139276

•(AlxGa1−x)2O3 films were deposited on 4H-SiC substrates through RF sputtering.•The annealing temperature of 800 °C formed the crystalline structure Ga2O3.•Bandgap widening of (AlxGa1−x)2O3 was achieved through RF sputtering.•The highest charge carrier mobility and concentration were obtained with 0.4 al.•The resulting device has improved or maintained electrical characteristics. In this work, (AlxGa1−x)2O3 thin films were grown on a 4H-SiC substrate by radio frequency (RF) sputtering. (AlxGa1−x)2O3 targets with different nominal Al content xt: 0, 0.1, 0.4, 0.8, and 1 were used for RF sputtering. Samples were subsequently annealed at 800 °C to enhance film crystallinity. X-ray diffraction analysis revealed the improved crystallinity for increased Al content (xt), ranging from a ratio of 0 to 0.4 (in relation to Al+Ga content). The films with Al content of 0.8 and 1 exhibited poor crystallinity. The chemical compositions of the Al, Ga, and O atoms were consistent with those of the sputtering targets. Furthermore, the analysis of the inelastic energy loss from X-ray photoelectron spectroscopy confirmed that bandgap tuning is possible for (AlxGa1−x)2O3 using the RF sputtering method. Hall mobility improved up to 17.1%, from 21.90 (xt: 0) to 25.65 (xt: 0.4) cm2V−1s−1. I−V characteristics corresponded well with the Hall measurement. Therefore this study effectively demonstrated the tuning of the bandgap of (AlxGa1−x)2O3 by varying the Al composition. Further, the electrical properties of the (AlxGa1−x)2O3 can be improved or maintained from that of conventional Ga2O3 devices by optimizing the growth ambient.