Kwon Jin-Beom, Kim Sae-Wan, Kang Byoung-Ho, Yeom Se-Hyuk, Lee Wang-Hoon, Kwon Dae-Hyuk, Lee Jae-Sung, Kang Shin-Won
School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Daegu, 702-701, Republic of Korea.
Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi, 39253, Republic of Korea.
Nano Converg. 2020 Aug 17;7(1):28. doi: 10.1186/s40580-020-00238-3.
InGaAs-based photodetectors have been generally used for detection in the short-wave infrared (SWIR) region. However, the epitaxial process used to grow these materials is expensive; therefore, InGaAs-based photodetectors are limited to space exploration and military applications. Many researchers have expended considerable efforts to address the problem of SWIR photodetector development using lead sulfide (PbS) quantum dots (QDs). Along with their cost-efficient solution processability and flexible substrate compatibility, PbS QDs are highly interesting for the quantum-size-effect tunability of their bandgaps, spectral sensitivities, and wide absorption ranges. However, the performance of PbS QD-based SWIR photodetectors is limited owing to inefficient carrier transfer and low photo and thermal stabilities. In this study, a simple method is proposed to overcome these problems by incorporating CdS in PbS QD shells to provide efficient carrier transfer and enhance the long-term stability of SWIR photodetectors against oxidation. The SWIR photodetectors fabricated using thick-shell PbS/CdS QDs exhibited a high on/off (light/dark) ratio of 11.25 and a high detectivity of 4.0 × 10 Jones, which represents a greater than 10 times improvement in these properties relative to those of PbS QDs. Moreover, the lifetimes of thick-shell PbS/CdS QD-based SWIR photodetectors were significantly improved owing to the self-passivation of QD surfaces.
基于铟镓砷（InGaAs）的光电探测器通常用于短波红外（SWIR）区域的探测。然而，用于生长这些材料的外延工艺成本高昂；因此，基于InGaAs的光电探测器仅限于太空探索和军事应用。许多研究人员付出了巨大努力，以解决使用硫化铅（PbS）量子点（QD）开发SWIR光电探测器的问题。除了具有成本效益的溶液加工性和与柔性衬底的兼容性外，PbS量子点因其带隙、光谱灵敏度的量子尺寸效应可调性以及宽吸收范围而备受关注。然而，基于PbS量子点的SWIR光电探测器的性能受到低效载流子转移以及光稳定性和热稳定性较低的限制。在本研究中，提出了一种简单的方法来克服这些问题，即在PbS量子点壳层中掺入硫化镉（CdS），以提供高效的载流子转移，并增强SWIR光电探测器抗氧化的长期稳定性。使用厚壳PbS/CdS量子点制造的SWIR光电探测器表现出11.25的高开/关（光/暗）比和4.0×10琼斯的高探测率，相对于PbS量子点，这些性能有超过10倍的提升。此外，由于量子点表面的自钝化，厚壳PbS/CdS量子点基SWIR光电探测器的寿命得到了显著提高。
