| Summary: | 碩士 === 中華大學 === 電機工程學系碩士班 === 99 === In recent years, with the public demand for wireless products is growing, thus creating a high-power semiconductor device on the required output is also higher, although the traditional substrate materials have a process to produce cheap price stability and overall advantages of total . However, the elements subject to their own characteristics, the performance is not high-power family of elements with a few components compared to the material which is currently popular AlGaN / GaN transistors formed. GaN has a high power, high temperature, high breakdown voltage, high current density, high-frequency characteristics of good performance, wireless transmission products now required for high-power amplifier has great appeal.
GaN transistors in the substrate self-heating caused by poor heat dissipation problems, resulting in reduced transistor performance. GaN transistors with different substrate materials such as SiC, Si, Sapphire for the combination can improve the heat dissipation and have different performance characteristics. The advantage of SiC substrate using a high heat capacity, the thermal conductivity of 4.9 W / cm K is three time for the GaN (1.5W/cm K). The temperature can up to 400°C or more. However, SiC substrates is too expensive. The silicon substrate is good candidate for GaN transistors due to its low cost, large area and high electrical conductivity (heat). GaN transistors with high-power, High temperature, high breakdown voltage and high current density on different substrate can further develop high efficiency, large area, low cost devices in the next generation. In this thesis, we used SiC and Si substrate to study the selft heating effect of GaN. Pulse IV and Load Pull measurements also be used to analysis the self heating effect and electrical degradation of GaN devices.
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