GaN-based HEMT Device Integration And The Output Characteristics Research

AlGaN/GaN heterostruetures have been a subject of intense investigation because they are currently the most important and most essential structures for developing GaN based high temperature,high frequency,and high power microwave electron devices. AlGaN/GaN heterostruetures have large band offset and strong polarization,which make the sheet carrier concentration of the two dimensional electron gas up to 1013/cm2 without intentional doping. The stress will be introduced to the channel of AlGaN / GaN-HEMT for modulating the concentration of 2DEG through the structure of micro-cantilever in this paper. Design and fabrication the sensor based power-electric coupling and research the output characteristics of GaN/AlGaN-HEMT device as innovation to start work. The major results are listed.1. The hexagonal wurtzite structure GaN films without cracks have been grown on the 3-inch Si (111) substrates by MOCVD process. From the results of X-ray diffraction we find the (0002) face as GaN films main crystal face. Through the analysis of Raman spectroscopy, we can calculate the residual stress in Si (530MPa) and GaN (250MPa). The film surface is smooth and the roughness is less than 0.72nm in the range of 2μm×2μm by atomic force microscopy (AFM) observations.2. From the measurement of X-ray double crystal rocking curve, we can calculate the values of the screw-type (Dscrew=7×108cm-2), the edge-type (Dedge=2.9×109cm-2) and the mixed (3.6×109cm-2) dislocation density. These indicate that the crystal quality of epitaxial GaN films near the level of sapphire as substrate. The stress sensing properties of GaN films based on Si substrate is obvious and the value up to 93.5MPa/um.3. Design a new micro-structure which integrated the GaN/AlGaN-HEMT device with micro- cantilever and research the key technology in the fabricating process. Using the process of controlling hole so that we can control the thickness of cantilever and mass accurately. Based on the experiments relative to the fabrication technology,the GaN/AlGaN-HEMT device integrated micro-structure was successfully fabricated. The results of Raman testing showed that the HEMT device at the root of cantilever suffered the maximum stress which consistent with design ideas and simulation results.4. The test results of HEMT device output characteristics indicate that: the temperature coefficient of HEMT device maximum saturation current is 0.058 mA/K which testing by high and low temperature equipment. What's more, the relationship between the temperature and output saturation current of the device follows the trend of I∝T-1 (200K