Synthesis and Characterization of Bulk and Two-Dimensional Gallium Selenide

Undergraduate #317
Discipline:
Subcategory: Materials Science

Sean Mileski - Pennsylvania State University
Co-Author(s): Natalie Briggs and Joshua Robinson, Pennsylvania State University, University Park, PA

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Gallium Selenide (GaSe) is a hexagonal layered structure with many potential applications in optoelectronics. Two-dimensional Gallium Selenide (GaSe) exhibits desirable physical properties that are not present in its bulk form, such as a 2eV direct bandgap and high photoresponse.1 However, reliable synthesis of 2D GaSe through powder vaporization methods is challenging due to a wide range of growth parameters that may be used, environmental impacts, and the lack of a high quality, bulk synthetic precursor. To investigate how high quality, 2D GaSe may be reliably synthesized, we have first synthesized bulk GaSe precursor in a tube furnace system, and characterized it with X-ray diffraction (XRD) for 1:1 stoichiometry and uniformity, and Raman Spectroscopy. Following this process, 2D GaSe was synthesized using bulk GaSe precursors and was characterized with Atomic Force Microscopy (AFM) to determine how the quality of bulk GaSe affected the properties of 2D GaSe crystals. Growth parameters of the tube furnace system were optimized to improve quality and achieve reliable synthesis of 2D GaSe. Samples of bulk GaSe that were the most physically uniform were the most effective precursors for 2D GaSe. Higher temperature, pressure, and Argon gas flow rate resulted in higher quality 2D GaSe synthesis.

Funder Acknowledgement(s): National Science Foundation

Faculty Advisor: Joshua Robinson, jrobinson@psu.edu

Role: I conducted the growths of both bulk and 2D Gallium Selenide. I also performed characterization tests on the materials: (Optical Microscopy, Atomic Force Microscopy, Raman Spectroscopy, X-Ray Diffraction).