H2-INDUCED CHANGES IN ELECTRICAL CONDUCTANCE OF BETA-GA2O3 THIN-FILM SYSTEMS

H-2-induced changes of electrical conductivity in polycrystalline, undoped beta-Ga2O3 thin films in the temperature range of 400-650-degrees-C are described. The sheet conductance of these films depends reversibly, according to a power law sigma-square approximately p1/3, on the partial pressure of hydrogen in the ambient atmosphere of the Ga2O3 film. A bulk vacancy mechanism is excluded by experiments and it is shown that the interaction is based on a surface effect. Changes in conductance are discussed to result from the formation of an accumulation layer due to chemisorption on the grain surfaces. Typical coverages are determined to be approximately 10(-4) ML for pH2 = 0.05 bar and T = 600-degrees-C. A possible explanation of the sigma-square approximately p1/3 power law is provided.