Introduction metalorganic chemical vapor deposition, hydride vapor phase

Introduction  GaN (gallium nitride) is one of the third generation of wide band gap semiconductors in Materials Chemistry. Compared with formal semiconductor materials, GaN (gallium nitride) has a higher frequency, higher power, and higher density for making integrated electronics, besides, the strong radiation resistance ability for GaN (gallium nitride) could also make great contributions in microwave power devices filed too.Properties for GaN (gallium nitride)  Preparation for GaN (gallium nitride)The preparation of GaN (gallium nitride) includes four main steps: metalorganic chemical vapor deposition, hydride vapor phase epitaxy, separation and second growth.In the MOCVD step, ultra-pure gases are transferred into a reactor and finally result in a deposition of a very thin layer of atoms onto a semiconductor wafer. For instance, Pin can be grown in a heated substrate by trimethylindium and phosphine.The precursor molecular decomposition happens in the absence of oxygen. As to the equipment, the reaction chamber is the main body that is composed by reactor walls, liner, susceptor, gas injection units and temperature control units.Besides, two temperature should be paid attention when we heat the substrate. One is around 823K and another is around 1273K. In the low temperature condition, there will be a buffer layer growing firstly. However, in the high temperature, GaN (gallium nitrate) will grow directly.  So the temperature should be controlled.The hydride vapor phase epitaxy (HVPE) makes the GaN (gallium nitrate) grow continually. The hydrogen chloride is reacted at elevated temperature while the group (III) metal producing gaseous metal chlorides and then it will react with ammonia to produce group (III) metal nitride.As to the separation part, the technique of laser lift-off is better than natural separation which uses high power pulsed laser directly to the surface. The energy of light is between Esubstrate and EGaN.Applications  One of the typical application for GaN (gallium nitride) is power devices. Compared GaN (gallium nitride) with other materials, it has relatively small volume and high efficiency to transport. Nowadays, as the popularization of 4G cell site and wireless power, the potential market could be expected too. Besides from the strong ability for GaN (gallium nitride) to transport information, the high color rendeing index and luminous efficiency of GaN (gallium nitride) also could be applied to the LED.For instance, many companies have put their eye on the research and exploitation on GaN (gallium nitride) materials, like Samsung, Mitsubishi etc. According to the graph mentioned on the slides, it can easily show us the promising future of GaN (gallium nitride), the statistics also show that the total value in US in 2015 has arrived at 298 millionDollars, and many of the cost is concentrated on wireless infrastructure.

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