非晶氧化物InGaZnO4 薄膜製備的透明薄膜電晶體

Abstract

本論文研究以非晶氧化物InGaZnO (a-IGZO)透明半導體薄膜，來製備透明薄膜電晶體元件。霍爾量測顯示：在室溫下、氧氣壓力介於20~200 mtorr沉積的非晶相InGaZnO 薄膜，薄膜載子濃度介於1019~1021 cm-3、電阻率ρ約10-3（Ω-cm）、電子遷移率介於20~25 cm2V-1s-1。其與金屬及銦錫氧化物(ITO)的接面具有蕭基接面(Schottky contact)的性質。利用室溫下Lift-off製程以及底部閘極結構，我們得到可見光(λ=400~700 nm)平均透光率86.3%、元件遷移率μsat=7~19 cm2V-1s-1、開關電流比~106以及關閉時低電流10-12 A的元件特性。這些特性已經達到元件應用於平面顯示器的需求；然而開啟時電流非線性現象與電流衰減則尚待努力。

In this thesis, we study the transparent thin film transistors fabricated by amorphous InGaZnO4 (a-IGZO) thin films. The Hall measurements indicate that the carrier concentration of a-IGZO film is between 1019~1021 cm-3, resistivity ρ is around 10-3 (Ω-cm), and electron mobility is between 20~25 cm2V-1s-1 repectively. Films were deposited with O2 pressure between 20~200 mtorr. The contact between film and metal as well as indium-tin oxide (ITO) all showed the Schottky contact behavior. The devices, fabricated by a bottom gate structure combined with lift-off process at room temperature, show an average transmission (λ=400~700 nm) of 86.3%, saturation mobility μsat=7~19 cm2V-1s-1, on-off ratio reaches ~106, and low off current around 10-12A. The performances of devices are satisfactory for flat panel display applications. However, the non-linear characteristics of I-V and the current decay in large bias regime remain to be explored and improved.