Numerical analysis of carbon concentration in GaN films growth via MOCVD in horizontal reactor
| Autor: | YE,ZHENG-WEI, 葉政緯 |
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| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 In recent years, GaN film materials are regarded as one of important future semiconductor materials because of their high temperature resistance, high voltage resistance and low resistance. Gallium nitride is produced by metal organic chemical vapor deposition (MOCVD). Epitaxial growth using trimethylgallium (TMGa) and ammonia (NH3) as precursors. In order to achieve the requirements of semiconductor components, controlling the resistance value of gallium nitride is very important. When the carbon concentration is too high, the resistance is also too high, so controlling the carbon content of the film is an important point. Since GaN cannot measure the carbon-containing gas in the reactor during the experiment, it is impossible to accurately understand the chemical reaction in the gas phase. Therefore, it is important to establish a numerical model containing the carbon reaction. In the past,references have been established the gallium nitride carbon-containing reaction model with different temperatures, according to the references the carbon concentration also varies with the pressure, carrier gas, and ammonia flow. Our study will establish the model that carbon concentration related to temperature, pressure, and gas flow. The model is used to further investigate the effect of carbon on the film in the variation of various parameters. Then the results of the study show when the temperature rises, the carbon concentration will decrease due to the increase of the desorption rate. When the pressure rises, the adsorption flux of gallium nitride and carbonaceous species will increase. However,the pressure will affect the desorption rate.So the carbon concentration will decreases. In addition, when the flow rate of trimethylgallium increases, the carbon concentration increases due to the pyrolysis to produce more carbon species. When the ammonia flow rate increases, the reaction between methyl and ammonia accelerates and the product methane is not easy to adsorb. The methane will decrease the carbon concentration. Finally, when the hydrogen flow rate rises, the carbon concentration will decrease as the hydrogen reduces the main carbon-adsorbed species. After the simulation results, it can be concluded that a film with a lower carbon concentration can epitaxy by having a high temperature, a high pressure, a high ammonia gas, a high hydrogen gas, and a low trimethylgallium flow rate in the process. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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