Thickness dependent metal-insulator transition and dimensional crossover for weak localization in Si_(0.02)Zn_(0.98)O thin films grown by pulsed laser deposition

摘要

Metal to insulator transition was observed in Si_(0.02)Zn_(0.98)O (SZO) films, grown by pulsed laser deposition on sapphire substrates, as the thicknesses of the films were reduced from ～40 to 15 nm. The SZO film with thickness of ～40nm showed typical metallic behavior in temperature dependent resistivity measurements. On the contrary, the SZO film with thickness of ～15nm was found to exhibit strong localization where the transport at low temperature was dominated by variable range hopping conduction. In the intermediate thickness regime, quantum corrections were important and a dimensional crossover from 3D to 2D weak localization occurred in the SZO film with thickness of 20 nm.