Lukman Steven, Ding Lu, Xu Lei, Tao Ye, Riis-Jensen Anders C, Zhang Gang, Wu Qing Yang Steve, Yang Ming, Luo Sheng, Hsu Chuanghan, Yao Liangzi, Liang Gengchiau, Lin Hsin, Zhang Yong-Wei, Thygesen Kristian S, Wang Qi Jie, Feng Yuanping, Teng Jinghua
Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.
Department of Physics, National University of Singapore, Singapore, Singapore.
Nat Nanotechnol. 2020 Aug;15(8):675-682. doi: 10.1038/s41565-020-0717-2. Epub 2020 Jun 29.
The development of infrared photodetectors is mainly limited by the choice of available materials and the intricate crystal growth process. Moreover, thermally activated carriers in traditional III-V and II-VI semiconductors enforce low operating temperatures in the infrared photodetectors. Here we demonstrate infrared photodetection enabled by interlayer excitons (ILEs) generated between tungsten and hafnium disulfide, WS/HfS. The photodetector operates at room temperature and shows an even higher performance at higher temperatures owing to the large exciton binding energy and phonon-assisted optical transition. The unique band alignment in the WS/HfS heterostructure allows interlayer bandgap tuning from the mid- to long-wave infrared spectrum. We postulate that the sizeable charge delocalization and ILE accumulation at the interface result in a greatly enhanced oscillator strength of the ILEs and a high responsivity of the photodetector. The sensitivity of ILEs to the thickness of two-dimensional materials and the external field provides an excellent platform to realize robust tunable room temperature infrared photodetectors.
红外光电探测器的发展主要受到可用材料选择和复杂晶体生长过程的限制。此外，传统III-V族和II-VI族半导体中的热激活载流子使得红外光电探测器的工作温度较低。在此，我们展示了由钨和二硫化铪（WS/HfS）之间产生的层间激子（ILE）实现的红外光电探测。该光电探测器在室温下工作，并且由于大的激子结合能和声子辅助光学跃迁，在更高温度下表现出更高的性能。WS/HfS异质结构中独特的能带排列允许从短波到长波红外光谱进行层间带隙调谐。我们推测，界面处相当大的电荷离域和ILE积累导致ILE的振子强度大大增强以及光电探测器的高响应度。ILE对二维材料厚度和外部场的敏感性为实现稳健的可调室温红外光电探测器提供了一个极好的平台。
