Controlled Vapor Phase Growth of Single Crystalline, Two-Dimensional GaSe Crystals with High Photoresponse

Journal Article · Wed Jan 01 04:00:00 EST 2014 · Scientific Reports

DOI:https://doi.org/10.1038/srep05497· OSTI ID:1150344

Li, Xufan ^[1]; Lin, Ming-Wei ^[1]; Zhang, Huidong ^[2]; Puretzky, Alexander A ^[1]; Idrobo Tapia, Juan C ^[1]; Ma, Cheng ^[1]; Chi, Miaofang ^[1]; Yoon, Mina ^[1]; Rouleau, Christopher M ^[1]; Kravchenko, Ivan I ^[1]; Geohegan, David B ^[1]; Xiao, Kai ^[1]

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1. ORNL
2. University of Tennessee, Knoxville (UTK)

Abstract Compared with their bulk counterparts, atomically thin two-dimensional (2D) crystals exhibit new physical properties, and have the potential to enable next-generation electronic and optoelectronic devices. However, controlled synthesis of large uniform monolayer and multi-layer 2D crystals is still challenging. Here, we report the controlled synthesis of 2D GaSe crystals on SiO2/Si substrates using a vapor phase deposition method. For the first time, uniform, large (up to ~60 m in lateral size), single-crystalline, triangular monolayer GaSe crystals were obtained and their atomic resolution structure were characterized. The size, density, shape, thickness, and uniformity of the 2D GaSe crystals were shown to be controllable by growth duration, growth region, growth temperature, and argon carrier gas flow rate. The theoretical modeling of the electronic structure and Raman spectroscopy demonstrate a direct-to-indirect bandgap transition and progressive confinement-induced bandgap shifts for 2D GaSe crystals. The 2D GaSe crystals show p-type semiconductor characteristics and high photoresponsivity (~1.7 A/W under white light illumination) comparable to exfoliated GaSe nanosheets. These 2D GaSe crystals are potentially useful for next-generation electronic and optoelectronic devices such as photodetectors and field-effect transistors.

• Research Organization: Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences (CNMS)
• Sponsoring Organization: ORNL LDRD Director's R&D
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1150344
• Journal Information: Scientific Reports, Journal Name: Scientific Reports Vol. 4
• Country of Publication: United States
• Language: English