為增加網路頻寬與速度，光訊號的偵測以及編碼能力，已成為下一世代通訊與運算元件之核心技術。本研究以溶液法製備鋅錫氧化物(Zinc Tin Oxide，簡稱ZTO)薄膜作為電晶體通道層，選用可見光雷射光(405、520以及635奈米)來激發ZTO內部的中性氧空缺，使其離子化為帶正電氧空缺(V_O^(2+))，並伴隨著光電子產生，造成光響應電流。由於激發ZTO的中性氧空缺需要UV光或是波長小於400 奈米之可見光，為增加ZTO可反應的可見光波段，本研究在ZTO通道層底下埋入金奈米粒子，利用金奈米粒子吸收500奈米~600奈米區間的可見光，進而透過表面電漿共振效應產生熱電子，並導入ZTO通道，增加光響應電流。此外，也希望藉由金奈米粒子捕捉/釋放電子的效應，以達到記憶體的功能表現。
從紫外可見光吸收圖譜中可以發現，金奈米粒子在約520奈米波段確實有明顯的吸收峰，另透過FDTD模擬ZTO與金奈米粒子在520奈米光源照射下，產生的電場變化分佈，發現金奈米粒子表面周圍的ZTO具有較強的電場，藉此來證明金奈米粒子之表面電漿共振效應確實會影響ZTO之電場變化。此外，相較於金奈米粒子置於ZTO表面的結構，將金奈米粒子埋在ZTO底下，對於ZTO的電場變化影響是更加明顯。藉由量測電晶體ID-VG曲線，發現添加金奈米粒子元件因為表面電漿共振的作用，對於520奈米雷射光之光響應度可提高2.2倍。
另外，在照光(405、520以及635奈米)期間施加負閘極偏壓(VG= -40 V)，可使原本被ZTO與SiO2介面缺陷所捕捉的電子被釋放出來，進而貢獻到光電流中，對於未添加金奈米粒子之元件，光響應度最大增幅四倍。透過照光期間施加閘極偏壓(VG= -40 V)的操作方式，可使金奈米粒子修飾氧化鋅錫電晶體之光響應度最大增幅達到13倍，其主要原因為帶正電氧空缺會受到負閘極偏壓的吸引，而聚集在ZTO與金奈米粒子之介面，藉此減小蕭特基能障的寬度，增加電子從金奈米粒子穿隧至ZTO之機率，造成光電流的改變。
為了進一步表現出元件之光記憶特性，本研究以“照光(405、520以及635奈米)期間施加閘極偏壓(VG= -40 V)”的方式當作寫入操作，寫入時間為一秒，以閘極偏壓VG= 0 V以及汲極偏壓VD= 10 V讀取寫入後的汲極電流值。透過上述的操作方式，三種照光波長的寫入條件皆可使添加金奈米粒子元件最少達到六個截然不同的組態，以及具有超過4000秒的電流持久度。反觀沒有添加金奈米粒子之元件，在如此短時間的寫入操作下，僅能對405奈米的光源產生光反應，而表現出多重汲極電流組態以及電流持久度，對於520奈米以及635奈米光源的光反應太過於微弱，難以有多重組態以及穩定的光電流。

In this study, we report a dual-functional hybrid device which can work as both a photo-sensing transistor and a photo-memory by embedding Au NPs in the zinc-tin oxide (ZTO) thin film transistor. Au NPs not only act as the charge trapping/detrapping layer but also the LSPR media which can transfer hot electrons to ZTO channel layer. The ZTO/Au NPs hybrid device shows a photoresponsivity ∼200 % higher than that of bare ZTO thin film transistor under 520 nm light illumination. Due to the effect of electron tunneling from Au NPs to ZTO, the photoresponsivity of ZTO/Au NPs hybrid device to 405, 520 and 635 nm light under the negative gate bias is further increased by >500, >300 and >1300 %, respectively.
Multilevel photo-memory performance is also demonstrated under repeated light and gate bias co-stimulation for 1 s, for at least 6 multiple memory states. The multilevel photo-memory performance of ZTO/Au NPs hybrid device is attributed to Au NPs which donate the hot electrons to ZTO during the co-stimulation. The excess electrons show a superb retention characteristic because there are not many recombination counterparts (i.e., charged oxygen vacancies (VO^(2+))) in the ZTO channel.

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