High mobility amorphous InGaZnO4 thin film transistors formed by CO2 laser spike annealing

Abstract

Amorphous InGaZnO4 (a-IGZO) thin film transistors (TFTs) hold great potential for large area and flexible electronics with current research focused on improving the mobility and stability. In this work, we report on properties of IGZO TFTs fabricated using laser spike annealing (LSA) with a scanned continuous wave CO2 laser. For peak annealing temperatures near 430 °C and a 1 ms dwell, TFTs exhibit saturation field-effect mobilities above 70 cm2/V-s (Von ∼ −3 V), a value over 4 times higher than furnace-annealed control samples (∼16 cm2/V-s). A model linking oxygen deficient defect structures with limited structural relaxation after the LSA anneal is proposed to explain the observed high mobility. This mobility is also shown to be comparable to the estimated trap-free mobility in oxide semiconductors and suggests that shallow traps can be removed by transient thermal annealing under optimized conditions.