Annealing Induced Semiconductor-Metal Transition in Ge+ITO Film

We report significant changes in the electrical properties of a thin film consisting of closely packed Ge quantum dots formed in an ITO matrix by magnetron sputtering, upon annealing. Prior to the treatment, the system shows semiconducting behavior where the carrier density can be easily modulated with a gate. After heating, a huge change in the resistivity of more than seven orders of magnitude is observed, and the system now shows metallic behavior as evidenced by the temperature dependence of the resistivity. The arrangement and size properties of the quantum dots remain the same before and after annealing, and the determined electrical properties are then attributed to the changes in the crystalline structure of the system.