Effect of the V/III ratio during buffer layer growth on the yellow and blue luminescence in undoped GaN epilayer has been studied by means of photoluminescence spectroscopy and high resolution X-ray diffraction.It is ...Effect of the V/III ratio during buffer layer growth on the yellow and blue luminescence in undoped GaN epilayer has been studied by means of photoluminescence spectroscopy and high resolution X-ray diffraction.It is found that the densities of screw and edge threading dislocations increase with the V/III ratio of the buffer layer,and the intensities of the yellow luminescence(YL) and blue luminescence(BL) emissions also increase dramatically.However,the density ratio of the edge threading dislocation to the screw threading dislocation remains invariant,as well as the intensity ratio of YL emission to BL emission.It can be concluded from these phenomena that the edge threading dislocation and screw threading dislocation can enhance the YL and BL emissions,respectively.展开更多
Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied t...Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied to some complicated statistics. In this paper, to test the difference between coefficients of two linear regression models, the authors apply JEL to construct the confidence regions. Based on the 3EL ratio test, a version of Wilks＇ theorem is developed. Furthermore, to improve the coverage accuracy of confidence regions, a Bartlett correction is applied. Simulation studies are carried out to show the effectiveness of the proposed method in aspects of coverage accuracy. A real data set is analyzed with the proposed method as an example.展开更多
基金supported by the Special Funds for Major State Basic Research Project (Grant Nos.2011CB301900,2012CB619304,and 2012CB619200)the Hi-tech Research Project (Grant No.2011AA03A103)+4 种基金the National Natural Science Foundation of China (Grant Nos.60990311,60820106003,60906025,60936004,and 61176063)the Natural Science Foundation of Jiangsu Province (Grant Nos.BK2008019,BK2011010,BK2010385,BK2009255,and BK2010178)the Program Granted for Scientific Innovation Research of College Graduate in Jiangsu Province (Grant No.CXLX12_0049)the Research Funds from NJU-Yangzhou Institute of Opto-electronicsa project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Effect of the V/III ratio during buffer layer growth on the yellow and blue luminescence in undoped GaN epilayer has been studied by means of photoluminescence spectroscopy and high resolution X-ray diffraction.It is found that the densities of screw and edge threading dislocations increase with the V/III ratio of the buffer layer,and the intensities of the yellow luminescence(YL) and blue luminescence(BL) emissions also increase dramatically.However,the density ratio of the edge threading dislocation to the screw threading dislocation remains invariant,as well as the intensity ratio of YL emission to BL emission.It can be concluded from these phenomena that the edge threading dislocation and screw threading dislocation can enhance the YL and BL emissions,respectively.
基金supported by the China Postdoctoral Science Foundation under Grant No.2014M550799the National Science Foundation of China under Grant No.11401561
文摘Empirical likelihood has been found very useful in many different occasions. It usually runs into serious computational difficulties while jackknife empirical likelihood （JEL） is shown to be effective when applied to some complicated statistics. In this paper, to test the difference between coefficients of two linear regression models, the authors apply JEL to construct the confidence regions. Based on the 3EL ratio test, a version of Wilks＇ theorem is developed. Furthermore, to improve the coverage accuracy of confidence regions, a Bartlett correction is applied. Simulation studies are carried out to show the effectiveness of the proposed method in aspects of coverage accuracy. A real data set is analyzed with the proposed method as an example.
