非晶氧化銦鎵鋅薄膜電晶體對動態光照及正向偏壓之時間響應的研究

Abstract

非晶銦鎵鋅氧化物（α-IGZO）薄膜晶體管（TFT）具有許多的優點，使之被期待可以用來改善像素的開口率以及應用在透明電產品上，但是其在於光照以及偏壓下產生的不穩定特性將是一項重要的議題，因此我們將在本研究中探討 α-IGZO在光照以及偏壓下的時間響應。我們重複了以前對於在單一脈衝光以及正偏壓下汲極電流隨時間改變量的實驗，並且藉由將擬合參數由固定的常數改為隨時間變化的變數來修改從前的擬合公式，這個新的擬合可以很好的擬合實驗結果甚至能夠預測超過實驗量測範圍的汲極電流變化量。在這份研究中透過分析在不同量測時間以及光照強度下擬合參數的變化來解釋時間響應的機制，為了要探討更真實的照光情況，我們研究了在複數脈衝光單一強度、複數脈衝光複數強度以及隨機波形的照光條件下的時間響應，我們試著使用單一脈衝光的量測結果以及修改後的擬合公式來建立用來預測複雜照光條件的資料庫，接著我們藉由反應機制建立了這些複雜照光情況下的預測程序，並且使用預測資料庫以及預測程序來進行預測並且與實驗結果比較。預測的結果相當不錯，雖然在預測回復行為特別是隨機波形的照光情況下時的誤差較大，此結果指出這些預測程序在大部分的狀況下都能適用。這份研究顯示了大部分的照光後汲極電流變化都是可以預測的，可以做為α-IGZO 透明電子產品開發的參考。

The amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) can be expected to improve the pixel aperture ratio and possible to be applied in transparent electronics for its many advantages. However, the light illumination and the gate bias stress induced instability is a critical issue for the a-IGZO TFTs. Therefore, we investigated the time response of the a-IGZO TFTs under light illumination and bias stress in this work. We repeated the drain current change under single-pulse light illumination measurement from the previous study and modified its fitting formula by changing the fitting parameters from constant to time dependent variables. The new fitting formula can well fit the measurement result and further predict the drain current change beyond the measurement scope. The mechanism for the response behaviors is also explained through analyzing the fitting parameters at different measurement time and under different light intensities in this work. In order to investigate the more real illumination situations, we studied the time response to multi-pulse single-level, multi-pulse multi-level and arbitrary waveform light illumination. We tried to use the single-pulse measurement result and the modified fitting formula to build the prediction data base for the prediction work of those complex illumination situations. We then proposed the prediction procedures for those complex illumination situations based on the mechanism while using these prediction procedures and the prediction data base to do the prediction work and compare it to the measurement results. The prediction results are quite well, even though the error of the predicted recovering behavior is relatively larger, especially for the arbitrary waveform light illumination. It indicates that the prediction procedures are available in most illumination situations. This work reveals that most of the drain current response during and after light illumination is predicable, which might be used in the development of a-IGZO TFTs transparent electronics.