探討沉積鈣鈦礦材料之電子傳輸特性

Abstract

近年來研究指出鈣鈦礦材料使用於太陽能電池中可具有高能量轉換效能等特點，因此鈣鈦礦材料在光電元件上應用的課題備受關注。我們以兩段式旋轉塗佈法沉積高純度鈣鈦礦材於矽基板上，並使用此鈣鈦礦材料製作場效應電晶體。從元件樣品中測量鈣鈦礦電晶體之場效電晶體效應，並改變溫度及照光等變化來量測電性。我們觀察到電阻隨著溫度下降而增加之趨勢，說明鈣鈦礦材料表現出半導體電性行為。此外在照光下量測鈣鈦礦電晶體電性，照光後電阻為未照光前電阻之0.01倍左右。因照光與未照光前後電阻差異達一百倍，顯示其應用在光偵測器元件方面的潛力。分析鈣鈦礦電子傳輸特性，我們發現其電子傳輸特性符合Mott三維電子變程跳耀傳輸機制，分析結果顯示其無序特性，從擬合數據計算出在溫度為100 K及300 K時鈣鈦礦薄膜的電子跳耀能量約97 meV及220 meV。

Due to their high energy conversion efficiencies in solar cells, CH3NH3PbI3 perovskites have attracted much attention in optoelectronic applications. Here we deposit high quality thin films of CH3NH3PbI3 perovskites on Si wafers by using a two-step spin coating method, and we try several methods to make field-effect transistors. In this study, we demonstrate the field-effect behavior, the temperature behavior, and the light illumination behavior of the CH3NH3PbI3 perovskite devices. It is found that the resistance decreases with increasing temperatures, indicating the semiconducting behavior almost without impurity doping in our CH3NH3PbI3 perovskites. On the other hand, the resistance under light illumination drops to be two orders of magnitude smaller than that in dark. That implies promising and great potentials as an effective photodetector. After analyzing electron transport behaviors of our CH3NH3PbI3 perovskite devices, we confirm the best fitting and explanation of the data by using the theory of Mott’s three-dimensional variable range hopping by which the disorder parameter T_0 is evaluated. The hopping energy of 97 and 220 meV at 100 and 300 K, respectively, are evaluated for our CH3NH3PbI3 perovskites.