Enhanced Photocurrent and Suppressed Dark Current of MXene/Ge Heterostructure-Based Near-Infrared Photodetectors Enabled by Surface Charge Transfer Induced Inversion Layer

• Published in: IEEE transactions on electron devices pp. 1 - 7
• Main Authors: Xie, Chao, Cheng, Yu, Liu, Shisi, Xu, Shijie, Cui, Xisheng, Yang, Liangpan, Yang, Wenhua, Huang, Zhixiang
• Format: Journal Article
• Language: English
• Published: IEEE 24.10.2024
• Subjects: 2-D material; Dark current; Detectors; Electrons; Germanium; heterostructure; inversion layer; Junctions; near-infrared (NIR) photodetector; Performance evaluation; Photoconductivity; Photodetectors; Substrates; surface charge transfer doping; Surface treatment
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2024.3480891

2-D MXene/narrow-gap material heterostructures represent a class of hopeful platforms for highly efficient and low-budget near-infrared (NIR) photodetection. Nonetheless, performance improvement is astricted by the comparatively low junction barrier height due to minor work function discrepancy between two components. In this work, a surface inversion layer is introduced between 2-D MXene film and n-Ge substrate exploiting a surface charge transfer doping technique. The coating of MoO<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> layer with a high work function induces spontaneous electron extraction from n-Ge toward MoO<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> layer. The charge transfer produces a p-type inversion layer on n-Ge surface, which markedly enhances built-in electric field and restrains photocarrier recombination. As a consequent, the optoelectronic performance of a 2-D MXene/Ge heterostructure-based NIR light detector is greatly improved. Specifically, the responsivity and specific detectivity are enhanced from 370.9 <inline-formula> <tex-math notation="LaTeX">\text{mA}\cdot \text{W}^{-\text{1}}</tex-math> </inline-formula> and 2.22 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{\text{11}}</tex-math> </inline-formula> Jones to 702.5 <inline-formula> <tex-math notation="LaTeX">\text{mA}\cdot\text{W}^{-\text{1}}</tex-math> </inline-formula> and 1.17 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{\text{12}}</tex-math> </inline-formula> Jones, respectively, upon 1550-nm light illumination at self-driven working mode. Around one order of magnitude suppression in dark current is observed. In addition, the detector exhibits quick response speed of 25.2/31.8 <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>s and robust operational durability as well. The present study provides a hopeful scheme for further improving the property of 2-D material/semiconductor heterostructure-based photoelectronic devices.