AlGaN/InGaN异质结中一种新缺陷的TEM表征

TEM Characterizing of a New Defect in AlGaN/InGaN Heterostructures

对用金属有机物化学气相沉积法(MOCVD)在蓝宝石(Al2O3)衬底上生长的紫外光发光二极管(UV-LED)圆晶片进行了透射电子显微镜(TEM)观察研究。发现在外延膜的表面交错存在着一种宽300～700nm、长达数十微米以上的带状缺陷。这种缺陷存在于AlGaN/InGaN组成的多层量子阱区,它还能作为位错发射源在(0001)面和{1122}面上产生大量的位错环。对材料的发光性能造成严重影响。根据位错滑移和多层膜的成分来看,这种缺陷是由于拉应力引起的。

UV-LED die grown on Al2O3 substrate using MOCVD was investigated,a kind of new defect was found in AlGaN/InGaN multi-quantum wells region.These defects presented in a band shape on the upper surface of epitaxial film with width varied from 300 to 700 nm and compose of a network structure.Tensile stress is supposed to initiate the formation of these band defects.A large amount of dislocation loops were emitted from these band defects and propagated on the(0001)plane and the inclined {1122} planes,respectively.The band defects together with the dislocation loops are very deleterious to light emission property of the epitaxial film.According to the dislocation slip and the component of multi-layer films,the defect is due to the tensile stress.