State Key Laboratory of Metastable Materials Science and Technology, Yanshan University , Qinghuangdao 066004, PR China.
ACS Appl Mater Interfaces. 2016 Feb;8(7):4781-8. doi: 10.1021/acsami.5b12137. Epub 2016 Feb 15.
Single-layer WS2 has shown excellent photoresponse properties, but its promising applications in high-sensitivity photodetection suffer from the atomic-thickness-limited adsorption and band-gap-limited spectral selectivity. Here we have carried out investigations on WS2 monolayer based phototransistors with and without decoration of SnSe nanocrystals (NCs) for comparison. Compared to the solely WS2 monolayer, SnSe NCs decoration leads to not only huge enhancement of photoresponse in visible spectrum but also extension to near-infrared. Under excitation of visible light in a vacuum, the responsivity at zero gate bias can be enhanced by more than 45 times to ∼99 mA/W, and the response time is retained in millisecond level. Particularly, with extension of photoresponse to near-infrared (1064 nm), a responsivity of 6.6 mA/W can be still achieved. The excellent photoresponse from visible to near-infrared is considered to benefit from synergism of p-type SnSe NCs and n-type WS2 monolayer, or in other words, the formed p-n heterojunctions between p-type SnSe NCs and n-type WS2 monolayer.
单层 WS2 表现出优异的光电响应特性，但由于原子层厚度的限制吸附和带隙限制的光谱选择性，其在高灵敏度光电探测中的应用受到限制。在这里，我们对具有和不具有 SnSe 纳米晶体 (NCs) 修饰的 WS2 单层光电晶体管进行了研究，以便进行比较。与单纯的 WS2 单层相比，SnSe NCs 修饰不仅导致可见光光谱中的光电响应大大增强，而且还扩展到近红外光。在真空中可见光激发下，零栅偏压下的响应率可增强 45 倍以上，达到约 99 mA/W，响应时间保持在毫秒级。特别是，随着近红外光（1064nm）的光电响应的扩展，仍可实现 6.6 mA/W 的响应率。从可见光到近红外的优异光电响应被认为受益于 p 型 SnSe NCs 和 n 型 WS2 单层的协同作用，或者换句话说，在 p 型 SnSe NCs 和 n 型 WS2 单层之间形成了 p-n 异质结。
