Epitaxial Tantalum-Doped β-Ga2O3 Thin Films Grown on Mgo (001) Substrate by Pulsed Laser Deposition

Epitaxial thin films of tantalum-doped beta-Ga2O3 (Ta-Ga2O3) are grown on MgO (001) substrates to study the effect of Ta doping on the electrical properties of beta-Ga2O3 films. X-Ray diffraction (XRD) measurements show that the films with different Ta doping concentrations are (00l)-oriented single-crystalline beta-Ga2O3 without impurity phases. The incorporation of the Ta element modifies the electrical properties of Ta-Ga2O3 films significantly. At a very low doping ratio of 0.05 mol%, the Ta-Ga2O3 film showed a minimum resistivity of 2.32 Omega cm and a carrier concentration of 2.48 x 10(17) cm(-3). The corresponding activation energy of Ta element in the film is 16.8 meV, suggesting that the Ta element is a promising shallow donor dopant. The X-ray photoelectron spectroscopy (XPS) analysis confirms that the Fermi level of the Ga2O3 films shifts toward the conduction band minimum after the introduction of Ta ions. These results indicate that the transition metal element Ta could be an effective n-type dopant for modulating the carrier transport behavior of beta-Ga2O3 films.