Liquid phase growth of bulk GaSe crystal implemented with the temperature difference method under controlled vapor pressure

• Published in: Journal of crystal growth Vol. 380; pp. 18 - 22
• Main Authors: Onai, Takahide, Nagai, Yuki, Dezaki, Hikari, Oyama, Yutaka
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2013; Elsevier
• Subjects: A1. Crystal morphology; A2. Growth from solutions; Absorption coefficient; B1. Gallium compounds; B2. Nonlinear optic materials; Concentration (composition); Condensed matter: structure, mechanical and thermal properties; Controlled atmospheres; Cross-disciplinary physics: materials science; rheology; Crystal growth; Crystals; Defects and impurities in crystals; microstructure; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Growth from vapor; Materials science; Methods of crystal growth; physics of crystal growth; Nonlinear optical crystals; Optical materials; Optics; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Polytypes; Structure of solids and liquids; crystallography; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Vapor pressure; Vibration; A2. Growth from solutions; B1. Gallium compounds; B2. Nonlinear optic materials; A1. Crystal morphology; Crystal growth; Non linear material; Vapor pressure; Crystal growth from vapors; XRD; Absorption coefficients; Crystal perfection; Optical microscopy; Crystal morphology; Gallium compounds; Growth from solution; Defect density; Crystalline phase; Point defects; Surface morphology; Interference; Raman spectroscopy; Mechanical vibrations; Transmittance; Allotropy; Millimeter wave generation; Monocrystals; THz range; Growth mechanism
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.05.027

GaSe crystal has been expected as one of the promising nonlinear optical crystals for highly efficient terahertz (THz) wave generation. However there are several reasons why it is difficult to grow the bulk crystals with high quality. To overcome some difficulties, the temperature difference method under controlled vapor pressure (TDM-CVP) is applied for crystal growth. According to this method, stoichiometric composition can be controlled by the application of Se vapor during crystal growth. Crystal growth is carried out at a constant growth temperature without any mechanical disturbance or vibration. It is also noticed that lower temperature growth enables the reduction of point defect concentration in equilibrium. In this article, surface morphology is observed by an optical microscope using the Nomarski interference method. To identify polytypes of grown crystals, backscattered Raman spectra were measured. X-ray diffraction confirmed the polytypes and single crystalline phase. Infrared (λ=1μm) and terahertz wave (1–3THz) transmittance measurements were performed to calculate the absorption coefficient in these wavelength regions. From these results, it is shown that the grown crystals have shown ε-type single phase and the absorption coefficients of grown crystals have been improved according to the increase of applied Se vapor pressure during crystal growth. •GaSe crystals were grown by TDM-CVP.•Stoichiometric composition was controlled by application of Se vapor pressure.•ε-Type GaSe crystals were grown by TDM-CVP.•Light absorption characteristics were improved by increasing Se vapor pressure.