Comparative study of a-IGZO TFTs with direct current and radio frequency sputtered channel layers

摘要

In this work, a comparative study of electrical properties and gate-bias stress stability between direct current (DC)-sputtered and radio frequency (RF)-sputtered amorphous indium-gallium-zinc oxide thin film transistors (a-IGZO TFTs) is conducted. The RF-sputtered a-IGZO TFTs show higher field-effect mobility and steeper sub-threshold slope. The DC-sputtered ones show a better uniformity of threshold voltage, enhanced stability under both positive bias stress and negative bias illumination stress. The X-ray photoelectron spectroscopy characterization of the a-IGZO films reveals that the concentration of oxygen vacancies and electron density in the RF-sputtered a-IGZO film is higher than that in the DC-sputtered one, which probably accounts for the differences of electrical properties between the RF-sputtered and DC-sputtered a-IGZO TFTs.