Growth, characterization and application of In2Se3 crystals

• Main Authors: Ying-cen Chen, 陳映岑
• Other Authors: Ching-hwa Ho
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/6evg6k

碩士 === 國立臺灣科技大學 === 應用科技研究所 === 102 === Single crystals of γ-In2Se3 and α-In2Se3 were grown by chemical vapor transport method using ICl3 as a transport agent. X-ray diffraction and transmission electron microscopy (TEM) measurements confirmed α-In2Se3 belongs to two-layer hexagonal structure (2H) and γ-In2Se3 has a defect wurtzite structure (Hexagonal, H). Both γ-In2Se3 and α-In2Se3 display stacking-layers structure. Transmission electron microscope and Raman measurements show amorphous (disordered and polycrystalline) state of the γ-phase In2Se3. The amorphous effects present on the γ-In2Se3 layers show thickness-dependent optical-absorption edge and thickness-dependent resistivity. A thermoreflectance (TR) and transmission measurements confirmed γ-In2Se3 is a direct-gap semiconductor with thickness (t) dependent energy gap of 2.08 eV (t=290um) ~ 2.52 eV (t=6um). The Photo-voltage-current measurements of different-thickness γ-In2Se3 layers verified that as the thickness of γ-In2Se3 decreases, the absorption edge of the polycrystal blue shifts, and shows high sensitivity to the blue-UV illuminations. The laser-induced photodarkening and annealed recovery test also verified that γ-In2Se3 is an erasable read/write optical-memory material.