Spectromicroscopy and imaging of photoexcited electron dynamics at in-plane silicon pn junctions

Aiqin Hu; Wei Liu; Xiaofang Li; Shengnan Xu; Yaolong Li; Zhaohang Xue; Jinglin Tang; Lulu Ye; Hong Yang; Ming Li; Yu Ye; Quan Sun; Qihuang Gong; Guowei Lu

doi:10.1039/D0NR07954E

Spectromicroscopy and imaging of photoexcited electron dynamics at in-plane silicon pn junctions†

Aiqin Hu,^a Wei Liu,^a Xiaofang Li,^a Shengnan Xu,^b Yaolong Li,^a Zhaohang Xue,^a Jinglin Tang,^a Lulu Ye,^a Hong Yang,^acd Ming Li,^e Yu Ye,

^a Quan Sun,

^d Qihuang Gong^acd and Guowei Lu

*^acd

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* Corresponding authors

^a State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of the Ministry of Education, School of Physics, Peking University, Beijing 100871, China
E-mail: guowei.lu@pku.edu.cn

^b State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China

^c Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China

^d Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, Jiangsu, China

^e Institute of Microelectronics, Peking University, Beijing 100871, China

Abstract

The ultrafast spatiotemporal imaging of photoexcited electrons is essential to understanding interfacial electron dynamic processes. We used time- and energy-resolved photoemission electron microscopy (PEEM) to investigate the photoexcited electron dynamics at multiplex in-plane silicon pn junctions. We found that the measured kinetic energy of photoelectrons from n-type regions is higher than that from p-type regions owing to different work functions. Interestingly, the kinetic energy of outer n-type regions is higher than that of inner n-type regions, which is caused by the reverse bias induced by photoemission. Time-resolved PEEM results reveal different evolution rates of hot electrons in different doping regions. The rise time of the n-type (outer n-type) regions is faster than that of the p-type (inner n-type) regions. So, closed doping patterns can influence the electron spectra and dynamics at the micro-nano scale. These results help us to understand the ultrafast dynamics of carriers at in-plane interfaces and optimize optoelectronic integrated devices with complex heterojunctions.

Nanoscale

Spectromicroscopy and imaging of photoexcited electron dynamics at in-plane silicon pn junctions†

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Spectromicroscopy and imaging of photoexcited electron dynamics at in-plane silicon pn junctions

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