液相磊晶生長砷化鋁鎵氧化層之研製與應用

• Main Authors: Hong-June Li, 黎鴻俊
• Other Authors: Liann-Be Chung
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/48875732825989678746

碩士 === 中正理工學院 === 電機工程研究所 === 86 === Abstract Gallium Asenide (GaAs) compound semiconductor are widely used in high speed devices, because of their high mobility in contrast to silicon. However, the main advantage of silicon is its ability to form high quality thermal oxides, which lead to the development of Si-based metal-oxide-semiconductor(MOS) devices in today's integrated circuit technology. If an oxide formed on GaAs could be equivalent to silicon dioxide, high performance metal-oxide-semiconductor field effect transistors (MOSFET) could be made by GaAs-related materials. Therefore, many different approaches to form GaAs oxides have been investigated, such as dry or wet thermal oxidation, plasma oxidation and anodic oxidation. Unfortunately, the oxide quality is still not good enough to use as gate insulator. Recently, the thermally formed native oxides of AlGaAs, consisting of aluminum-oxygen complex, have been studied and exhibited better oxide quality. Therefore, in this paper, the oxidation of AlGaAs is studied. The AlGaAs samples were prepared by liquid phase epitaxy(LPE). The Al0.77Ga0.23As epitaxial layer will be grown by a growth rate of 0.72μm at a temperature of 800oC. The Al0.77Ga0.23As epitaxial layer with the thinnest thickness of 570nm can be obtained by a growth period of one second. Several methods were used to prepare the AlGaAs oxides in this paper. First, a dry oxidation method with various oxidation temperatures is used to grow the AlGaAs oxides. It is observed that the Al0.77Ga0.23As oxides grown by an oxidation temperature of 650oC show better oxide surface and an oxidation rate of 10 nm/min is obtained. In addition, it is found that the Al0.77Ga0.23As oxides grown by an oxidation time of 40 minutes exhibit better electrical property than the others. Then, Anodic oxidation with various electrolyte solutions, such as H2O2 solution, tartaric acid and ethylene glycol mixing solution as well as pure deionized water solution, is also used to prepare Al0.77Ga0.23As oxides. It is found that the Al0.77Ga0.23As oxides grown by pure water demonstrated the best oxide quality than the other electrolyte solutions. Using pure deionized water as electrolyte can avoid the contamination. However, the oxide prepared by room-temperature anodic oxidation is still good enough to become as gate oxides. Therefore, furnace oxidation or annealing is used to further improve anodic oxide quality. It is found that the anodic oxides followed by oxidation temperature of 600oC demonstrated the best oxide quality than the other one and the anodic oxide followed by annealing temperature of 400oC also exhibited better oxide quality than the other one. It is interesting to note that, to obtain high oxide quality, the anodic oxides followed by oxidation treatment need high oxidation temperature, but by annealing must be annealed at lower temperature. Although the mechanism of this phenomena is unclear now, it is believed that the methods proposed by this paper will provide a potential candidates to prepare high quality AlGaAs oxides.