Controlled vapor phase growth of single crystalline, two-dimensional GaSe crystals with high photoresponse

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...

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Bibliographic Details
Published in:Scientific reports 2014-06, Vol.4 (1), p.5497-5497, Article 5497
Main Authors: Li, Xufan, Lin, Ming-Wei, Puretzky, Alexander A, Idrobo, Juan C, Ma, Cheng, Chi, Miaofang, Yoon, Mina, Rouleau, Christopher M, Kravchenko, Ivan I, Geohegan, David B, Xiao, Kai
Format: Article
Language:English
Subjects:
Argon
Crystals
Illumination
Photoresponse
Raman spectroscopy
Spectroscopy
Temperature effects
Vapors
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Summary: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 μm in lateral size), single-crystalline, triangular monolayer GaSe crystals were obtained and their structure and orientation were characterized from atomic scale to micrometer scale. 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.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep05497