快速脈衝光照在正向偏壓下對非晶矽氧化銦鎵鋅薄膜電晶體汲極電流響應之研究

Abstract

非晶銦鎵鋅氧化物（α-IGZO）薄膜電晶體（TFTs）擁有許多的優點，如高的電子遷移率以及好的穿透度，使之可以被期待用來改善像素的開口率以及廣泛地使用在透明電子產品上，然而在應用上，其對於光照以及偏壓下所產生的不穩定特性是一項重要的議題，因此在這次究中我們將探討α-IGZO TFTs在穩定正向偏壓以及多個快速脈衝光照下的特性。我們將量測在不同光強以及脈波頻率下汲極電流的改變對於時間的響應現象，此種不同光強以及脈波頻率下的照光響應行為可以被配適公式以及配適參數適當地分析，而所提出的解釋機制為氧空缺與光誘發的電子電洞對反應，此機制也可以妥善地解釋量測結果。分析的趨勢顯示出並非所有的氧空缺與電子電洞對的反應擁有相同的反應速率，我們首次發現可以快速反應的氧空缺數量會隨著光強的增加而遞增，並隨著脈衝頻率的增加而遞減，進一步地，我們提出了模型來描述氧空缺反應數量以及反應速率之間的關係。 這份研究實質上顯示了元件在多個快速脈衝光照下的時間響應其模型與機制，可以做為α-IGZO TFTs透明電子產品開發的有用參考。

The amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) possess many advantages, such as high mobility and good transparency, which can be expected to improve the pixel aperture ratio and widely used in transparent electronics. However, the instability under light illumination and gate bias stress is a critical issue in the application. In this work, the characteristic of the a-IGZO TFTs under steady positive bias and fast multiple-pulse illumination stress is analyzed. The change in the drain current (△ID) with respect to time is measured under different light intensities and pulse frequencies. The response behaviors can be well analyzed by the fitting formula and parameters for the different light pulse frequencies. And the proposed mechanism of the oxygen vacancy (Vo) reacting with the light-induced electron-hole (e-h) pairs is also well explaining the results. The tendency reveals that not all the Vo react with e-h pairs at the same reaction rate. It is observed for the first time that the number of Vo with fast reaction increases with the light intensity and decreases with the pulse frequency. Further, we proposed a model to describe the relation between the reaction number and the reaction rate of Vo. This work substantially proves the model and mechanism of time response to fast multiple-pulse light illumination, which can be a useful reference for the development of a-IGZO TFTs in transparent electronics.