Broadband and photovoltaic THz/IR response in the GaAs-based ratchet photodetector

Peng Bai; Xiaohong Li; Ning Yang; Weidong Chu; Xueqi Bai; Siheng Huang; Yueheng Zhang; Wenzhong Shen; Zhanglong Fu; Dixiang Shao; Zhiyong Tan; Hua Li; Juncheng Cao; Lianhe Li; Edmund Harold Linfield; Yan Xie; Ziran Zhao

doi:10.1126/sciadv.abn2031

Broadband and photovoltaic THz/IR response in the GaAs-based ratchet photodetector

Sci Adv. 2022 May 27;8(21):eabn2031. doi: 10.1126/sciadv.abn2031. Epub 2022 May 25.

Authors

Peng Bai¹, Xiaohong Li², Ning Yang¹, Weidong Chu¹, Xueqi Bai², Siheng Huang², Yueheng Zhang², Wenzhong Shen², Zhanglong Fu³, Dixiang Shao³, Zhiyong Tan³, Hua Li³, Juncheng Cao³, Lianhe Li⁴, Edmund Harold Linfield⁴, Yan Xie⁵, Ziran Zhao⁵

Affiliations

¹ Institute of Applied Physics and Computational Mathematics, Beijing 100088, China.
² Key Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
³ Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
⁴ School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK.
⁵ Department of Engineering Physics, Tsinghua University, Beijing 100084, China.

Abstract

High-performance broadband infrared (IR)/terahertz (THz) detection is crucial in many optoelectronic applications. However, the spectral response range of semiconductor-based photodetectors is limited by the bandgaps. This paper proposes a ratchet structure based on the GaAs/Al_xGa_1-xAs heterojunction, where the quasi-stationary hot hole distribution and intravalence band absorption from light or heavy hole states to the split-off band overcome the bandgap limit, ensuring an ultrabroadband photoresponse from near-IR to THz region (4 to 300 THz). The peak responsivity of the proposed structure can reach 7.3 A/W, which is five orders of magnitude higher than that of the existing broadband photon-type detector. Because of the ratchet effect, the proposed photodetector has a bias-tunable photoresponse characteristic and can operate in the photovoltaic mode with a broad photocurrent spectrum (18 to 300 THz). This work not only demonstrates a broadband photon-type THz/IR photodetector but also provides a method to study the light-responsive ratchet.