Improvement of electrical characteristics and stability of IGZO TFT through surface single crystallization of IGZO film at room temperature
The electrical characteristics and stability of indium gallium zinc oxide (IGZO) thin film transistors (TFTs) are improved through surface single crystallization of IGZO film by Cs ions adsorption at room temperature. The experimental results show that the Cs ions can bond with the oxygen ions in IGZO film, changing surface structure of IGZO film from amorphous to a single crystalline. The electrical properties and stability of surface single crystalline IGZO and a-IGZO based thin film transistors were investigated, respectively. With the introduction of the surface single crystalline of the IGZO film, the electrical properties of TFT were greatly improved, showing that the carrier mobility improved from 5.28 cm2 V−1s−1 to 8.84 cm2 V−1s−1, and the threshold voltage deceased from 7.6 V to 2.3 V, accompanied with a leakage current below 10−15 A. The stability of V th shifts in surface single crystalline IGZO based TFT was 6.3 V under VGS = 20 V for 5000 s, improved by ~32% compared with that of a-IGZO TFT.