MoS₂ 因其獨特的能帶結構與優異的光學性質，近年來成為極具研究價值的光電材料。單層 MoS₂ 為直接能隙半導體，能隙約為 1.8 eV，對可見光範圍具有強烈的吸收能力；而多層 MoS₂ 則轉變為間接能隙結構，能隙降至約 1.2 eV。這種能帶的可調控性使 MoS₂ 能涵蓋從可見光至近紅外的吸收範圍，提升其於多波段光偵測中的應用。此外，透過高功函數金屬與MoS₂ 形成的Schottky 接觸，具備內建電場及低暗電流的優勢，使其在光電轉換效率上表現出優異的光響應特性。 在本研究中，我們採用 VLS 法生長單層 MoS₂ 薄膜，並選擇鉍金（Bi/ Au）及低溫度下沉積金（Au）作為兩端金屬電極，製作出非對稱電極結構的 MoS₂ 蕭特基二極體。藉由低損傷的金屬沉積製程，可有效降低費米能階釘扎效應（Fermi level pinning），進而提升蕭特基能障高度（Schottky barrier, SB）。實驗結果顯示，所製作之元件展現出明顯的整流行為，整流比達156。 在光電特性方面，該元件於照光條件下能穩定產生的光電流，顯示出明確的光響應特性。進一步在入射光功率為0.89mW/cm2與反向偏壓為-1V條件下進行量測，計算出元件的光響應度最高為 3.41 A/W，偵測度為 4.61 × 10¹¹ Jones，顯示本元件具有優異的光偵測性能，具備作為二維光偵測元件的應用潛力。 ;Due to its unique band structure and excellent optical properties, MoS₂ has emerged in recent years as a highly valuable material for optoelectronic research. Monolayer MoS₂ is a direct bandgap semiconductor with a bandgap of approximately 1.8 eV, exhibiting strong absorption in the visible-light range, whereas multilayer MoS₂ transitions into an indirect bandgap structure with a reduced bandgap of about 1.2 eV. This tunable band structure enables MoS₂ to cover an absorption range from visible to near-infrared light, thereby enhancing its potential for multispectral photodetection. In addition, the Schottky contact formed between high-work-function metals and MoS₂ provides the advantages of an intrinsic built-in electric field and suppressed dark current, thereby enabling superior photoresponse characteristics in terms of optoelectronic conversion efficiency. In this study, monolayer MoS₂ films were grown using the VLS method, and asymmetric Schottky diodes were fabricated by employing bismuth/gold (Bi/Au) and low-temperature-deposited gold (Au) as the two metal electrodes. By adopting a low-damage metal deposition process, the Fermi level pinning effect was effectively suppressed, thereby enhancing the Schottky barrier height (SB). Experimental results demonstrated that the fabricated devices exhibited pronounced rectifying behavior with a rectification ratio of 156. In terms of photoelectric characteristics, the device generates stable photocurrents under illumination, exhibiting a distinct photoresponse behavior. Further measurements conducted under an incident optical power density of 0.89 mW/cm² and a reverse bias of −1 V revealed a maximum photoresponsivity of 3.41 A/W and a detectivity of 4.61 × 10¹¹ Jones, indicating that the device possesses excellent photodetection performance and holds great potential for applications as a two-dimensional photodetector.
