二維材料光電晶體研究開發

本論文中我們將看似不可行的材料─黑磷，從黑磷塊材上撕出奈米尺度的層狀黑磷並將其應用於電晶體中以用來探討奈米尺度下的二維黑磷材料的特性。因為黑磷本身有與空氣中水氧進行反應的趨勢，所以在此採用有別於一般二維材料的方法以保護黑磷來進行實驗。本論文中我們採用了溶液式撕裂法，這種作法是相對於用於黑磷的機械式撕裂法是容易與便宜許多的。參考許多類似的研究而進行實驗並就製程參數的修改與步驟改良並在最後撕出從原本是 200奈米長寬的片狀黑磷到接近微米尺度大小，而微米尺度大小的層狀黑磷讓我們可以進一步使用於電子束微影製成用於電晶體的製作，進而探討黑磷的光電特性。而我們在電晶體設置上採用了背閘極式場效電晶體的設計，這種設計著眼於可以先進行基板的製程再把黑磷轉印到基板上進而減少黑磷在製程過程中和大氣接觸的時間進而防止在製成過程中黑磷已經因為與水氧反應而效能衰退，而在本研究中黑磷因實驗需要而製於大氣下的時間是接近一小時。在電晶體製程完成後馬上光電特性的量測，從特性曲線和電流電壓特性曲線可以看到層狀黑磷是P型半導體特性並由特性曲線計算得黑磷場效電晶體的載子遷移率是365 cm2v-1s-1。而光特性的分析則得到層狀黑磷的光反應時間是在1.1微秒，在不同光強度去量測其光響應度是19.18 A/W。本研究中所製作出的光電晶體進行光電特行分析的結果顯示用溶液式撕裂法所製作出的光電晶體是可以和其他文獻中用機械式撕裂法所製作的黑磷電晶體有旗鼓相當的效能並顯示了層狀黑磷有很大的潛力用於電晶體和光偵測器這方面的應用。

關鍵字

二維材料；水溶液撕裂法；電晶體；黑磷；光電特性

並列摘要

In this thesis, we try to proceed from material exfoliation to device fabrication with the out-of-blue choice – black phosphorus (BP) as the main research target. BP itself with high risk to degrade in ambient leads to special ways be adopted for whole fabrication processes. Solution-based exfoliation method is taken in this work. This method is much lower cost comparing to traditional mechanical exfoliation and its transfer process is much easier for whole process taking place in glove box. We based on recent papers working on the same way to exfoliate BP and modified the process detail to optimize the flake size of BP for further fabrication. The flake size without optimization was around 200 nm * 200 nm which is too small for device fabrication even with e beam lithography and flake size after optimized was in submicron length and width (726 nm * 800 nm) which was much suitable for further device fabrication. In this work, back gate BP field-effect transistor (BP FET) was proceed and fabricated. With back gate FET design, we could reduce the time for BP put in ambient during process lowering the risk of BP itself degradation. The whole fabrication time for BP put in ambient was around an hour. The electrical and optical characteristics were measured right after device fabrication done. The transfer curve and I-V characteristic curve showed BP with p-type semiconductor characteristics and by calculation we got the mobility of the BP in ambient environment is 365 cm2v-1s-1 reaching the same level with similar work by other groups. BP FET’s optical characteristic was measured and its response time was 1.2 ms and its responsivity was 19.18 A/W. The result we got from measurement were compatible with other similar work with mechanical exfoliation way to achieve the same goal and demonstrate the potential of BP itself for application on transistor and photodetector.

並列關鍵字

2D material ； solution-based exfoliation ； transistor ； black phosphorus ； photo and electrical characteristic

參考文獻

[1] J. Bardeen and W. H. Brattain, “The Transistor, A Semi-Conductor Triode,” Phys. Rev. 74, 230 – Published 15 July 1948.

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[2] W. Shockley, “The Theory of p-n Junctions in Semiconductors and p-n Junction Transistors,” Bell System Technical Journal Volume 28, Issue 3, pages 435–489, July 1949.