Two-step chemical vapor deposition growth of MoS2-WSe2 heterojunction
| Autor: | Yi-Han Jiang, 江易翰 |
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| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 In this study, we demonstrated the characteristic and synthesis of heterojunction which was consisted of p-type tungsten diselenide (WSe2) and n-type molybdenum disulfide (MoS2). We used chemical vapor deposition (CVD) method to synthesize WSe2 and MoS2 on sapphire substrate. Optical microscope (OM) and scanning electron microscope (SEM) image was used to examine the morphology of thin films. Raman spectroscopy, photoluminescence spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscope (XPS) indicated the thickness, band gap energy and the elements composition of the as-prepared WSe2 and MoS2 samples. We showed electrical property of WSe2 and MoS2 transistors, WSe2 was typical of field effect transistor (FET) devices with p-type channel, and MoS2 was typical of FET devices with n-type channel. In order to fabricate the pn heterojunction diode, WSe2 was grown in the first step, followed by MoS2 CVD growth on the top surface of WSe2. In the voltage-current characteristic measurement, we demonstrated a clear current rectification behavior in the MoS2/WSe2 heterojunction diode, and the turn-on voltage was 0.5 V. Finally, we demonstrated the pnp heterojunction based on WSe2/MoS2/WSe2. The collector current increased as the base current became smaller. Compared to traditional bipolar junction transistor (BJT), we can find out the saturation region and the active region in the voltage-current plot. Therefore, we applied the pnp heterojunction to the switch circuit, we expect the heterojunction can be widely applied to the optoelectronic devices. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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