Thermally Phase-Transformed In2Se3 Nanowires for Highly Sensitive Photodetectors

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 10; no. 18; pp. 3795 - 3802
• Main Authors: Kang, Daegun, Rim, Taiuk, Baek, Chang-Ki, Meyyappan, M., Lee, Jeong-Soo
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 24.09.2014; Wiley Subscription Services, Inc
• Subjects: In2Se3; indium selenide; Nanotechnology; Nanowires; photodetectors; X-rays; α-phase; κ-phase; photodetectors; α-phase; In2Se3; κ-phase; indium selenide
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201400373

The photoresponse characteristics of In2Se3 nanowire photodetectors with the κ‐phase and α‐phase structures are investigated. The as‐grown κ‐phase In2Se3 nanowires by the vapor‐liquid‐solid technique are phase‐transformed to the α‐phase nanowires by thermal annealing. The photoresponse performances of the κ‐phase and α‐phase In2Se3 nanowire photodetectors are characterized over a wide range of wavelengths (300–900 nm). The phase of the nanowires is analyzed using a high‐resolution transmission microscopy equipped with energy dispersive X‐ray spectroscopy and X‐ray diffraction. The electrical conductivity and photoresponse characteristics are significantly enhanced in the α‐phase due to smaller bandgap structure compared to the κ‐phase nanowires. The spectral responsivities of the α‐phase devices are 200 times larger than those of the κ‐phase devices. The superior performance of the thermally phase‐transformed In2Se3 nanowire devices offers an avenue to develop highly sensitive photodetector applications. Improved photoresponse characteristics of thermally phase transformed In2Se3 nanowires for highly sensitive photodetectors are investigated. The phase transformation from κ‐phase to α‐phase is achieved by thermal annealing. The electrical and photoresponse characteristics are significantly enhanced in the α‐phase due to smaller bandgap structure compared to the k‐phase nanowires, leading to higher spectral responsivities.