ALD Al2O3 gate dielectric on the reduction of interface trap density and the enhanced photo-electric performance of IGO TFT

Abstract

The amorphous indium gallium oxide thin film transistor was fabricated using a cosputtering method. Two samples with different gate dielectric layers were used as follows: sample A with a SiO₂ dielectric layer; and sample B with an Al₂O₃ dielectric layer. The influence of the gate dielectrics on the electric and photo performance has been investigated. Atomic layer deposition deposited the dense film with low interface trapping density and effectively increased drain current. Therefore, sample B exhibited optimal parameters, with an I_on/I_off ratio of 7.39 × 10⁷, the subthreshold swing of 0.096 V dec⁻¹, and μ_FE of 5.36 cm² V⁻¹ s⁻¹. For ultraviolet (UV) detection, the UV-to-visible rejection ratio of the device was 3 × 10⁵, and the photoresponsivity was 0.38 A W⁻¹ at the V_GS of −5 V.