混合量子点-石墨烯光电探测器向亚波长尺寸的缩放
Scaling of Hybrid QDs-Graphene Photodetectors to Subwavelength Dimension
AI总结：
本文实验研究石墨烯-PbS胶体量子点光电晶体管缩至500 nm的几何效应，揭示光增益随1/LW缩放、接触与界面电荷转移限制性能，并提出光门控效率评估方法。
摘要：
新兴的胶体量子点（cQD）光电探测器目前在响应速度、光谱可调性、溶液可加工制造的简便性以及集成到弯曲或柔性衬底上的能力方面，对已确立的最先进红外光电探测器构成挑战。特别是基于二维材料和cQD的混合光电晶体管，因其固有的光增益能够实现光信号的直接增强而颇具前景。光增益对测量条件和光电探测器几何结构都很敏感，这使得文献中报道的器件之间的交叉比较相当复杂。在此，通过实验研究了器件长度L和宽度W向亚波长尺寸（尺寸小至500 nm）缩放对石墨烯-PbS cQD光电晶体管光响应的影响。研究发现，光增益和响应度按1/LW缩放，而光电流和比探测率与几何参数无关。测量是在缩放偏置电压条件下进行的，以获得可比较的电流。研究发现，对于L < 3 μm的器件，接触效应限制了光响应。详细研究了栅极电压、偏置电流、光强和频率与光响应之间的关系，并提出了一种用于评估cQD-石墨烯界面的光门控效率。特别是，研究发现10^8至10^9 Jones范围内的比探测率值（波长1550 nm、频率6 Hz、室温）受限于跨光敏界面的电荷转移。
英文摘要：
Emerging colloidal quantum dot (cQD) photodetectors currently challenge established state-of-the-art infrared photodetectors in response speed, spectral tunability, simplicity of solution processable fabrication, and integration onto curved or flexible substrates. Hybrid phototransistors based on 2D materials and cQDs, in particular, are promising due to their inherent photogain enabling direct photosignal enhancement. The photogain is sensitive to both, measurement conditions and photodetector geometry. This makes the cross-comparison of devices reported in the literature rather involved. Here, the effect of device length L and width W scaling to subwavelength dimensions (sizes down to 500 nm) on the photoresponse of graphene-PbS cQD phototransistors was experimentally investigated. Photogain and responsivity were found to scale with 1/LW, whereas the photocurrent and specific detectivity were independent of geometrical parameters. The measurements were performed at scaled bias voltage conditions for comparable currents. Contact effects were found to limit the photoresponse for devices with L < 3 μm. The relation of gate voltage, bias current, light intensity, and frequency on the photoresponse was investigated in detail, and a photogating efficiency to assess the cQD-graphene interface is presented. In particular, the specific detectivity values in the range between 10^8 to 10^9 Jones (wavelength of 1550 nm, frequency 6 Hz, room temperature) were found to be limited by the charge transfer across the photoactive interface.
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