Selective-area growth of GaN nanocolumns on Si(111) substrates for application to nanocolumn emitters with systematic analysis of dislocation filtering effect of nanocolumns
Selective-area growth of GaN nanocolumns on Si(111) substrates for application to nanocolumn emitters with systematic analysis of dislocation filtering effect of nanocolumns
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DOI：
10.1088/0957-4484/26/22/225602
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发表时间：
2015-06-05
期刊：
影响因子：
3.5
通讯作者：
Ishizawa, Shunsuke
中科院分区：
文献类型：
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作者：
Kishino, Katsumi;Ishizawa, Shunsuke
在Si(111)衬底上生长了直径从122 nm到430 nm的高度均匀的GaN纳米柱阵列。利用硅上AlN/GaN超晶格(SL)缓冲液获得的具有平坦表面(均方根表面粗糙度为0.84 nm)的GaN薄膜模板的使用，有助于在射频等离子体辅助分子束外延中使用厚度为5 nm的薄钛掩模来高质量地选择性地生长纳米柱。尽管GaN模板中含有大量的位错(位错密度接近10(11)cm(-2))，但随着纳米柱直径(D)的减小，其位错过滤作用增强。通过系统的电子显微镜观察，我们首次解释了纳米柱中位错扩展行为与纳米柱直径的关系。对于D=120-324 nm的纳米柱，在其底部上方300 nm的高度水平切片，进行平面图的透射电子显微镜分析，并通过对D类似于200 nm的纳米柱的横截面观察，分析位错在纳米柱中的传播。结果表明，位错在纳米柱底部300 nm区域得到了有效的过滤，纳米柱的位错密度随D的减小而减小，且窄纳米柱的位错密度随D的减小而减小
The growth of highly uniform arrays of GaN nanocolumns with diameters from 122 to 430 nm on Si (111) substrates was demonstrated. The employment of GaN film templates with flat surfaces (root mean square surface roughness of 0.84 nm), which were obtained using an AlN/ GaN superlattice (SL) buffer on Si, contributed to the high-quality selective-area growth of nanocolumns using a thin Ti mask of 5 nm thickness by rf-plasma-assisted molecular beam epitaxy. Although the GaN template included a large number of dislocations (dislocation density similar to 10(11) cm(-2)), the dislocation filtering effect of nanocolumns was enhanced with decreasing nanocolumn diameters (D). Systematic transmission electron microscopy (TEM) observation enabled us to explain the dependence of the dislocation propagation behavior in nanocolumns on the nanocolumn diameter for the first time. Plan-view TEM analysis was performed for nanocolumns with D=120-324 nm by slicing the nanocolumns horizontally at a height of similar to 300 nm above their bottoms and dislocation propagation through the nanocolumns was analyzed by the cross-sectional TEM observation of nanocolumns with D similar to 200 nm. It was clarified that dislocations were effectively filtered in the bottom 300 nm region of the nanocolumns, the dislocation density of the nanocolumns decreased with decreasing D, and for narrow nanocolumns with D