Structural, Optical, and Electrical Properties of Inox Thin Films Deposited by Peald for Flexible Device Applications

Abstract

Indium oxide (InO x ) thin films have attractive carrier transport properties for oxide semiconductors because of the large isotropic 5s orbital overlap in the In 3+ ions. In this study, InO x films were deposited by plasma-enhanced atomic layer deposition (PEALD). We evaluated the effects of the atomic layer deposition (ALD) process conditions such as process temperature, plasma power, and plasma duration time on the microstructure, physical, chemical, and electrical properties of the as-deposited InOx films. The InO x film deposited at an even growth temperature of 100 o C exhibited a polycrystalline structure without impurities. As growth temperature increased, the (222) orientation became favorable and the surface morphology of the as-deposited films improved. In addition, staggered-bottom gate structure thin-film transistors (TFTs) were fabricated to examine the feasibility of ALD-processed InOx film as a channel material for TFTs. As the growth temperature increased from 100 to 250 ℃, the mobility increased from 3.4 to 12.6 cm 2 /Vs and the hysteresis value decreased from 1.85V to 0.94V due to increasing carrier concentrations and decreasing defect states, respectively. Finally, a flexible device was fabricated on a Polyethylene naphthalate (PEN) substrate; the device parameters of V th and μ sat were determined to be 2.21 V and 16.6 cm 2 /Vs, respectively. These results demonstrate the potential for fabricating flexible TFT applications using plasma-enhanced atomic layer deposition.

Keywords: Indium Oxide (InOx), Plasma-Enhanced Atomic Layer Deposition (PEALD), DADI ([3-(dimethylamino)propyl] dimethyl indium) precursor, Crystallinity, Thin-Film Transistor (TFT)