Amorphous IGZO, Crystalline IGO, Amorphous IGZO Triple Active Layer With 2D Electron Gas at Both Interfaces for High Performance TFTs

ABSTRACT We report amorphous InGaZnO (a‐IGZO)/crystalline InGaO (C‐IGO)/a‐IGZO stack, thin‐film transistors (TFTs). The IGZO could not be crystallized but the IGO could be crystallized at 450°C. We fabricated dual‐gate C‐IGO TFTs with a‐IGZO layers interfaced with both the top and bottom gate insulators. Owing to the differences in optical bandgap and work function between a‐IGZO and C‐IGO, conduction band offsets is formed at the heterointerfaces, resulting in the formation of 2D electron gas (2DEG) in C‐IGO. The a‐IGZO/C‐IGO/a‐IGZO TFT demonstrates excellent electrical characteristics, exhibiting a threshold voltage (V TH ) of −0.8 V, field‐effect mobility (µ FE ) of 53.81 cm 2 V − 1 s − 1 , and subthreshold swing (SS) of 0.18 V/dec with excellent bias stability in dual‐sweep (DS) mode. Technology Computer Aided Design (TCAD) simulations reveal that electron transport is dominated by dual 2DEGs formed at the top and bottom heterointerfaces of the C‐IGO layer under dual‐gate operation.