Highly Responsive Ultrathin GaS Nanosheet Photodetectors on Rigid and Flexible Substrates

• Published in: Nano letters Vol. 13; no. 4; pp. 1649 - 1654
• Main Authors: Hu, PingAn, Wang, Lifeng, Yoon, Mina, Zhang, Jia, Feng, Wei, Wang, Xiaona, Wen, Zhenzhong, Idrobo, Juan Carlos, Miyamoto, Yoshiyuki, Geohegan, David B, Xiao, Kai
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 10-04-2013
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Devices; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Electronics; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Gallium - chemistry; Graphite - chemistry; Light; Materials science; Molecular electronics, nanoelectronics; Nanoparticles - chemistry; Nanostructure; Noise levels; Optoelectronic devices; Photocurrent; Photodetectors; Photoelectric effect; Physics; Polyethylene terephthalates; Polyethylene Terephthalates - chemistry; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon - chemistry; Silicon Dioxide - chemistry; Silicon substrates; Specific materials; Substrate Specificity; Surface Properties; photodetectors; photoresponsivity; two-dimensional materials; Gallium sulfide; nanosheets; Ethylene terephthalate polymer; Monolayer; Gallium arsenides; Polyethylene; Optoelectronics; Nanosheet; Molybdenum sulfide; Charge carrier mobility; Theoretical study; Valence band; Modeling; Photodetector; Indium arsenides; Nanoelectronics; Experimental result; Electronic structure; Graphene; Effective mass; Photoconductivity; Photoelectric current
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl400107k

The first GaS nanosheet-based photodetectors are demonstrated on both mechanically rigid and flexible substrates. Highly crystalline, exfoliated GaS nanosheets are promising for optoelectronics due to strong absorption in the UV–visible wavelength region. Photocurrent measurements of GaS nanosheet photodetectors made on SiO2/Si substrates and flexible polyethylene terephthalate (PET) substrates exhibit a photoresponsivity at 254 nm up to 4.2 AW–1 and 19.2 AW–1, respectively, which exceeds that of graphene, MoS2, or other 2D material-based devices. Additionally, the linear dynamic range of the devices on SiO2/Si and PET substrates are 97.7 dB and 78.73 dB, respectively. Both surpass that of currently exploited InGaAs photodetectors (66 dB). Theoretical modeling of the electronic structures indicates that the reduction of the effective mass at the valence band maximum (VBM) with decreasing sheet thickness enhances the carrier mobility of the GaS nanosheets, contributing to the high photocurrents. Double-peak VBMs are theoretically predicted for ultrathin GaS nanosheets (thickness less than five monolayers), which is found to promote photon absorption. These theoretical and experimental results show that GaS nanosheets are promising materials for high-performance photodetectors on both conventional silicon and flexible substrates.