Suppression of dislocation-induced spiral hillocks in MOVPE-grown AlGaN on face-to-face annealed sputter-deposited AlN template
Suppression of dislocation-induced spiral hillocks in MOVPE-grown AlGaN on face-to-face annealed sputter-deposited AlN template
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DOI：
10.1063/1.5141825
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发表时间：
2020-02
影响因子：
4
通讯作者：
K. Uesugi;K. Shojiki;Yuta Tezen;Y. Hayashi;H. Miyake
中科院分区：
文献类型：
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作者：
K. Uesugi;K. Shojiki;Yuta Tezen;Y. Hayashi;H. Miyake
采用金属有机气相外延(MOVPE)方法在溅射沉积AlN/蓝宝石(FFA Sp-AlN)模板上制备了AlGaN薄膜，并对其生长行为进行了研究。在FFA Sp-AlN模板上生长的蓝宝石衬底由于形成了较大的丘状结构，导致AlGaN的表面平整度较差。为了了解这些丘状结构的起源，对传统的完全MOVPE生长的AlN/蓝宝石(MOVPE-AlN)模板和FFA Sp-AlN模板的结晶度和表面形貌进行了综合研究。FFA Sp-AlN模板的螺纹位错密度约为1.8×106 cm−2，比MoVPE-AlN模板低两个数量级。因此，在FFA Sp-AlN模板中唯一观察到的丘状结构的生长归因于其低密度的螺型和混合型螺纹位错。大表面切割蓝宝石衬底抑制了FFA Sp-AlN模板上的丘状结构。表面平整度的改善导致了生长在AlGaN层上的多量子阱具有更好的光学性质。采用金属有机气相外延(MOVPE)方法在溅射沉积AlN/蓝宝石(FFA Sp-AlN)模板上制备了AlGaN薄膜，并对其生长行为进行了研究。在FFA Sp-AlN模板上生长的蓝宝石衬底由于形成了较大的丘状结构，导致AlGaN的表面平整度较差。为了了解这些丘状结构的起源，对传统的完全MOVPE生长的AlN/蓝宝石(MOVPE-AlN)模板和FFA Sp-AlN模板的结晶度和表面形貌进行了综合研究。FFA Sp-AlN模板的螺纹位错密度约为1.8×106 cm−2，比MoVPE-AlN模板低两个数量级。因此，在FFA Sp-AlN模板中唯一观察到的丘状结构的生长归因于其低密度的螺型和混合型螺纹位错。大面切开的S……
AlGaN films were grown on face-to-face annealed sputter-deposited AlN/sapphire (FFA Sp-AlN) templates via metalorganic vapor phase epitaxy (MOVPE), and the growth behavior of the AlGaN films was investigated. The sapphire substrates with small off-cut exhibited poor surface flatness of AlGaN grown on the FFA Sp-AlN templates owing to the formation of large hillock structures. To understand the origin of these hillock structures, the crystallinity and surface morphology of conventional fully MOVPE-grown AlN/sapphire (MOVPE-AlN) templates and the FFA Sp-AlN template were comprehensively studied. The screw- and mixed-type threading dislocation density of the FFA Sp-AlN template was estimated to be approximately 1.8 × 106 cm−2, which was two orders of magnitude lower than that of the MOVPE-AlN template. Consequently, the uniquely observed growth of the hillock structures in the FFA Sp-AlN templates was attributed to their low density of screw- and mixed-type threading dislocations. The large surface off-cut sapphire substrates suppressed the hillock structures on the FFA Sp-AlN templates. The improvement in surface flatness resulted in better optical properties of multiple quantum wells grown on the AlGaN layer. These results demonstrate a promising method for achieving highly efficient and cost effective AlGaN based deep ultraviolet light-emitting diodes.AlGaN films were grown on face-to-face annealed sputter-deposited AlN/sapphire (FFA Sp-AlN) templates via metalorganic vapor phase epitaxy (MOVPE), and the growth behavior of the AlGaN films was investigated. The sapphire substrates with small off-cut exhibited poor surface flatness of AlGaN grown on the FFA Sp-AlN templates owing to the formation of large hillock structures. To understand the origin of these hillock structures, the crystallinity and surface morphology of conventional fully MOVPE-grown AlN/sapphire (MOVPE-AlN) templates and the FFA Sp-AlN template were comprehensively studied. The screw- and mixed-type threading dislocation density of the FFA Sp-AlN template was estimated to be approximately 1.8 × 106 cm−2, which was two orders of magnitude lower than that of the MOVPE-AlN template. Consequently, the uniquely observed growth of the hillock structures in the FFA Sp-AlN templates was attributed to their low density of screw- and mixed-type threading dislocations. The large surface off-cut s...