Growth, structure and carrier transport properties of Ga2O3 epitaxial film examined for transparent field-effect transistor

• Published in: Thin solid films 2006-02, Vol.496 (1), p.37-41
• Main Authors: MATSUZAKI, Kosuke, HIRAMATSU, Hidenori, NOMURA, Kenji, YANAGI, Hiroshi, KAMIYA, Toshio, HIRANO, Masahiro, HOSONO, Hideo
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Laser deposition; Low-field transport and mobility; piezoresistance; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.08.187

Growth conditions of heteroepitaxial thin films of tin-doped Ga2O3 were surveyed from the viewpoint of visible application to field-effect transistors (FETs). Films were deposited by pulsed laser deposition, and post-annealing was examined to improve film structures. Atomically flat surfaces were obtained for films grown on yttria-stabilized zirconia (111) plane and post-annealed at 1400 DDGC, but they were insulating. Conductive heteroepitaxial films applicable to FETs were obtained on D*a-Al2O3 (0001) at specific deposition conditions, i.e. substrate temperatures from 500 to 550 DDGC and oxygen pressures from 5x10-4to 1x10-3Pa. It was found that the resulting epitaxial films have a crystal structure different from that of D*b-Ga2O3. The crystal lattice for the films is determined to be orthorhombic with a large possibility of a higher-symmetry hexagonal or rhombohedral system. The films exhibited high transparency in the near infrared-deep ultraviolet region and had bandgap of ~4DDT9 eV. The operation of top-gate MISFETs using the Ga2O3 film for the n channel was demonstrated.