物理学报2016，Vol.65Issue(16)：167201-1-167201-8,8.DOI:10.7498/aps.65.167201
一种测量纤锌矿n-GaN位错密度的新方法∗
A new metho d to determine the dislo cation density in wurtzite n-GaN
摘要
Abstract
We develop a new method to determine the edge and screw dislocation density in wurtzite n-GaN film. The method is to fit the van der Pauw variable temperature Hall-effect measurements with a analytic expression of low-field electron mobility in n-GaN. Our calculations take the comprehensive effect between the dislocation line and the shallow-donor defects as the main cause to depress the carrier mobility. Because of the crystal distortion near the dislocation line, the energy is so high that shallow-donor defects in the GaN crystal can be captured near the dislocation line. In other words, the shallow-donor defects distribute in lines along the dislocation line, but the shallow-donor defects along the screw and edge dislocation line have different energy levels. The shallow-donor defects take energy from lattice and the carrier, which is in relaxation process, then deliver the energy through ionizing. So, it is found that the following assumptions need to be made in order to obtain the model function for the mobility over a wide temperature range: i) there are 6 shallow-donor defect lines around one dislocation line;ii) two donor energy levels belonging to the screw and edge dislocation respectively must be taken into account; iii) the exchange energy between the carrier and the shallow-donor defect is~ωLO, the energy value of polar optical phonon. Under these assumptions, experiments indicate that our calculation function can fit the experimental curve best. The values of dislocation density from our model and others determined by x-ray diffraction or by chemical etching method are in good agreement, and the values of donor energy levels from our model and Rode iterative method to solve the Boltzmann equation are also in good accordance with each other. This method is applicable for the wurtzite n-GaN films grown by various preparation technologies under any condition, which is for the sample with the peak-mobility temperature about or under 200 K, not for the sample with the peak-mobility temperature about or above 300 K, which room-temperature mobility usually is about or less than 100 cm2/(V·s).关键词
氮化镓/霍尔迁移率/位错密度/Rode迭代法Key words
gallium nitride (GaN)/Hall mobility/dislocation density/rode iterative引用本文复制引用
何菊生,张萌,潘华清,齐维靖,李平..一种测量纤锌矿n-GaN位错密度的新方法∗[J].物理学报,2016,65(16):167201-1-167201-8,8.基金项目
江西省自然科学基金(批准号:20151BAB207066)和南昌大学科学技术学院自然科学基金(批准号:2012-ZR-06)资助的课题.* Project supported by the Natural Science Foundation of Jiangxi Province, China (Grant No.20151BAB207066) and the Natural Science Foundation of College of Science and Technology of Nanchang University, China (Grant No.2012-ZR-06) （批准号:20151BAB207066）
