蓝宝石衬底上RF-MBE生长的GaN中的极性控制和螺旋位错的降低

近年来人们报道了用MBE方法生长GaN的飞速进展,利用RF-MBE方法可以获得高的GAN生长速率和高的电子迁移率.本文讨论了用RF-MBE方法在蓝宝石衬底上生长GaN过程中的极性控制和螺旋位错的降低.在充分氮化的蓝宝石衬底上直接生长GaN,使GaN的极性控制为N-极性,并用高温生长的AlN核化层实现GaN的Ga-极性.对于N-和Ga-极性的GaN这两种情况,高温生长的AlN中间迭层的引入,可以有效地抑制螺旋位错的扩散.位错的降低使GaN的室温电子迁移率得到提高,对于Ga-极性的GaN,其值为332cm²/V·s;而对于N-极性的GaN,其值为688cm²/V·s.     

INTERIOR ERROR ESTIMATES FOR NONCONFORMING FINITE ELEMENT METHODS OF THE STOKES EQUATIONS

1.IntroductionInteriorerrorestimatesforfiniteelementdiscretizations(conforming)werefirstintroducedbyNitscheandSchatz[14]forsecondorderscalarellipticequationsin1974.Theyprovedthatthelocalaccuracyofthefiniteelementapproximationisboundedintermsoftwofact...     

Spin Trapping of the Phosphorus-centered Radicals Generated from Hydrogen Abstraction Reaction by 2,2-Diphenyl-1-picrylhydrazyl

IntroductionSPin trapping technique has been widely used for the detection and identification of unstable radicals. As traps, nitrones and nitroso compounds are most widely usedll--4]. However,the identification of spin adducts by EPR spectroscopy is rather difficult because the variationof the hyperfine coupling constants(hfccs) of spin adducts caused by the structural changes oftrapped radicals is not very large. Recently, the ph osp horns- con t al m ng m t rox id e h a s att ra ctedmuch …