Light interaction in InSe/GaSe van der Waals heterostructures
| Autor: | Chi-Chang Hsu, 徐啟昌 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 The two-dimensional heterostructures are bonded by van der Waals forces at the interface, different from three-dimensional materials which are connected by covalent bonds. These heterostructures lack dangling bonds and lattice mismatch. In addition, ultra-fast charge transfer in van der Waals heterostructures takes place within 50 fs. When incident light passes through the heterostructures, it engages in multiple reflections within the underlying substrates, producing interferences that lead to enhancement or attenuation of Raman intensities and photoluminescence intensities. Thus, the multiple boundaries and thickness of each material play a key role in the interaction of light and heterostructures and strongly affect the device performance. Gallium selenide (GaSe) and indium selenide (InSe) of IIIA-VIA groups have direct band gaps in few layers and multi-color photoresponse ranging from ultraviolet to near infrared. Therefore, in this study, InSe/GaSe and GaSe/InSe heterostructures were fabricated on wafers with silicon dioxide of different thicknesses. The interaction between the light and heterostructures was investigated by employing Raman and photoluminescence spectroscopy. From the results, the Raman intensities of the individual InSe, individual GaSe and junction are the strongest when the thickness of silicon dioxide is 270 nm. The Raman intensities of InSe and GaSe at the lower layer of the junction are higher than the upper layer. The photoluminescence intensity of GaSe at the lower layer of the junction is stronger than the upper layer. It is found that when the excitation wavelength is close to the band gap of GaSe, a resonance phenomenon occur at interface resulting in enhancement of Raman intensities. Based on the interference model, a strategy to modulate the photon and photoelectric properties of InSe/GaSe heterostructures and GaSe/InSe heterostructures is proposed which may provide new ways to improve the performance of optoelectronic devices such as LEDs and solar cells. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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