Photovoltaic and Photoconductive Action Due to PbS Quantum Dots on Graphene/SiC Schottky Diodes from NIR to UV
Photovoltaic and Photoconductive Action Due to PbS Quantum Dots on Graphene/SiC Schottky Diodes from NIR to UV
复制标题
石墨烯/SiC 肖特基二极管上的 PbS 量子点从近红外到紫外的光伏和光电导作用
DOI：
10.1021/acsaelm.9b00651
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发表时间：
2019
影响因子：
4.7
通讯作者：
Chandrashekhar, M. V.
中科院分区：
文献类型：
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作者：
Kelley, Mathew L.;Letton, Joshua;Simin, Grigory;Ahmed, Fiaz;Love-Baker, Cole A.;Greytak, Andrew B.;Chandrashekhar, M. V.
我们在n-碳化硅外延层上沉积了一层凝胶渗透层析纯化的PbS量子点(QD)，并在其上生长了10-15单层低漏厚的石墨烯(EG)肖特基接触，从而在器件中展示了对近红外光的光伏和光导响应。QD膜层可以通过选择性化学腐蚀来去除，重新设置EG/SiC肖特基二极管：亚带隙响应可以在随后的PBS-QD沉积中恢复。这些器件中的EG同时形成到SIC的肖特基触点和到PBS-QD的欧姆触点，从而实现了这些界面的电气屏蔽和彼此隔离。经过PbS-QD沉积后，二极管在远低于碳化硅禁带的光子能量处表现出光伏和光导响应，一直延伸到量子点薄膜的近红外禁带。扫描光电流显微镜显示，这是由于电荷从QD膜转移到n型4H-SiC层，通过与EG/SiC肖特基二极管平行的PbS-QD/SiC异质结(理想度n=2)。该量子点/碳化硅界面的光导增益可用于宽禁带平台的红外探测。高达40 ms的响应时间适用于成像应用，尽管需要谨慎的触点设计来优化功函数匹配和扩展电阻。
We demonstrate photovoltaic and photoconductive responses to near-infrared light in devices formed by depositing a film of gel permeation chromatography purified PbS quantum dots (QDs) on top of n-SiC epitaxial layers with natively grown, low-leakage 10–15 monolayer thick epitaxial graphene (EG) Schottky contacts. The QD film layer was removable by selective chemical etching, resetting the EG/SiC Schottky diode: the sub-bandgap response could be restored in subsequent PbS-QD depositions. The EG in these devices simultaneously forms Schottky contacts to SiC and ohmic contacts to PbS-QD, enabling electrical screening and isolation of these interfaces from each other. After PbS-QD deposition, the diodes exhibit photovoltaic and photoconductive responses at photon energies far below the SiC bandgap, extending to the NIR gap of the QD film. Scanning photocurrent microscopy illustrates that this is due to charge transfer from the QD film to the n-type 4H-SiC through a trap-limited, rectifying PbS-QD/SiC heterojunction with idealityn= 2 in parallel with the EG/SiC Schottky diode. The photoconductive gain at this QD/SiC interface could be useful for IR detection in wide-bandgap platforms. Response times as fast as 40 ms are suitable for imaging applications, although careful contact design is required to optimize work-function matching and spreading resistance.