宽带隙氮化镓(GaN)单晶材料可应用于制备高频、高功率、耐高温的微电子器件,实现发光波长覆盖整个可见光波段的光电子器件,在航空航天军事领域以及日常照明与显示等商业领域具有巨大的应用前景。目前较成熟的制备GaN材料的氢化物气相外延技术(HVPE)与金属有机化合物化学气相沉积(metal organic chemical vapor deposition,MOCVD)外延技术都是在异质衬底上生长的外延技术,由于衬底与外延层间的位错与热膨胀失配导致外延生长的晶体材料位错密度较高出现翘曲裂纹等现象,影响器件的工作效率及寿命,制约了其在半导体电子领域的应用。因此迫切需要高质量的块状单晶材料,剥离出GaN衬底从而实现同质外延技术。本论文分析研究了可望实现工业化量产的氨热法制备高质量大尺寸块状单晶材料的国内外研究现状、面临的挑战及其可观的应用前景。
p-type conductivity and crystal quality of Mg-doped GaN grown by MOCVD have been improved through opti- mization of the magnesium flow rate. The hole concentration first increased and then decreased with the magnesium...
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p-type conductivity and crystal quality of Mg-doped GaN grown by MOCVD have been improved through opti- mization of the magnesium flow rate. The hole concentration first increased and then decreased with the magnesium flow rate while the mobility decreased monotonously. The optimum sample reached a hole concentration of 4. 1×10^17cm -3 and a resistivity of 1Ω·cm. Based on a self-compensation model involving the deep donor Mo, VN, we calculate the hole con- centration as a function of magnesium doping concentration NA ,which indicates that the self-compensation coefficient in- creases with NA;the hole concentration first increases with NA and reaches a maximum at NA≈4×10^19 ,then decreases rapidly as doping concentration increases. XRD also indicate that dislocation density decreased as magnesium flow rate decreased.
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