超晶格插入层对Si基上GaN薄膜位错密度的影响

为了降低MOCVD外延生长Si基GaN的缺陷密度,尝试引入超品格插入层.界面突变的超晶格插入层能有效地阻挡由缓冲层延伸出来的位错.即使超晶格本身也产生位错,但位错的产生率比阻挡率低,所以超晶格总体起阻挡作用,可以减少后续生长的 HT-GaN(高温氮化镓)的位错密度.研究了超晶格厚度对 HT-GaN 的位错密度的影响.比较了超晶格厚度不同的3个样品,并采用高分辨双晶X射线衍射(DCXRD)对CaN进行结晶质量的分析,分别用 H3PO4 H2SO4 混合溶液和熔融 KOH 对样品进行腐蚀并用扫描电子显微镜(SEM)对腐蚀的样品进行观察.用 H3PO4 H2SO4 腐蚀过的样品比用KOH 腐蚀过的样品的位错密度大,进一步验证了之前有报道过的 H3PO4 H2SO4 溶液同时腐蚀螺位错和混合位错而 KOH只腐蚀螺位错.分析结果表明.引入适当厚度的超晶格插入层,可以有效地降低后续生长的 GaN 的位错密度.

Influence of the Thickness of Super Lattice Interlayer on the Dislocation Density of HT-GaN on Si(111)

To decrease the dislocation density of HT-C, aN on Si(111) with metalorganie chemical vapor deposition (MOCVD) ,super lattice interlayer is introduced. The super lattice with mutative interface can effectively prevent the dislocation originating from the buffer layer from penetrating to the surface of GaN film. The influence of the thickness of super lattice interlayer on the dislocation density of HT-GaN on Si(111) is investigated. Three sam- pies with different thickness of super lattice layer are studied. The high-resolution double crystal X-ray diffraction (DCXRD) is used to analyze the crystal quality. Furthermore, the three samples are etched by H3PO4+H2SO4mixed resolution and melted KOH respectively and then observed by scanning electron microscopy (SEM). The later experiment shown that the dislocation density of anyone of the three samples etched by H3PO4 + H2SO4mixed resolution apparently higher than that etched by melted KOH, which further justify the reported conclusion that H3PO4 +H2SO4 mixed resolution etch screw dislocation and mixture dislocation while melted KOH etch screw dislocation. Both experiments shows that modest thickness of super lattice interlayer effectively decline the disloca-tion density of HT-GaN on Si(111).