Atomic layer deposited p-type copper oxide thin films and the associated thin film transistor properties

Abstract

Copper oxide (CuOx) films were grown at a relatively low temperature (100 degrees C) by atomic layer deposition (ALD). Hexafluoroacetyl-acetonateCu(I)(3,3-Dimethyl-1-butene) ((hfac)Cu-(I)(DMB)) and ozone (O-3) were used as the copper precursor and oxidant, respectively. It is shown that stable phases of CuO are obtained through rapid thermal annealing (RTA) in air. After annealing at various temperatures (200-500 degrees C), different p-type band structures and electron binding information are obtained. X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) studies indicate that the major copper oxidation state changes from 1(+) to 2(+) during thermal treatment. Thin film transistors (TFTs) incorporating the ALD-grown CuOx semiconductors are evaluated, and an unusually high p-type device performance is observed, with a field effect mobility of 5.6 cm(2)/V s after annealing at 300 degrees C.