Effects of Sol-Gel Concentration and Annealing Condition on Performance of Zinc Tin Oxide Thin Film Transistor

• Main Authors: CHOU, CHENG-HAN, 周承翰
• Other Authors: HSU, CHIH-CHIEH
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/85k5z3

碩士 === 國立雲林科技大學 === 電子工程系 === 106 === In this research, we fabricated ZnSnO(ZTO) thin film transistor (TFT) by using a rapid and simple sol-gel method. The structure of the ZTO TFT was bottom-gate top-contact (BGTC). The structure was N+-Si/SiO2/ZnSnO/Al. To enhance the electrical properties of TFT, we controlled process conditions such as annealing temperature and ZTO solution molar concentration. The surface morphology, crystallinity, and electrical characteristics were analyzed. This thesis was divided into two parts. First, the temperature was increased from as-fabricated (200 ℃) to 700 ℃. According to previous literatures, Cl compounds in the ZTO channel layer could be considered as trap state, they act as obstacles for electron transportation for electrons in the conduction band, and they reduce mobility. When the annealing temperature is higher than 500 ℃, Cl compounds were decomposed, and switching characteristics were obtained for ZTO TFTs. It results from low trap state. The second part was ZTO solution molar concentration. The concentration conditions were 0.065 M, 0.096 M and 0.128 M. The Zn:Sn molar ratio of all conditions was 1:1. According to XRD and XPS analyzes, annealing at 600 ℃ and 0.096 M molar concentration can give a ZTO film having high crystallinity and low oxygen vacancy content. It results in an optimum ZTO TFT threshold voltage of -2.75 V, Ion/Ioff ratio of 1.12×1E8, mobility of 1.85 cm2/V∙s, and sub-threshold swing of 0.32 V/decade. The surface morphology and thicknesses of ZTO films were analyzed by using a field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The crystalline phase and crystallinity were examined by X-ray diffraction (XRD). The oxygen deficiency content and chemical bond were investigated by using an X-ray photoelectron spectroscopy (XPS). The electrical characteristic was measured by a Keysight 4156C semiconductor parameter analyzer.