Red Emission of Well‐Ordered InGaN/GaN Nanocolumn Arrays on Si (111) Substrates Grown via Nanotemplate Selective‐Area Growth

Herein, triangular‐lattice nanopillar templates are fabricated on sputter‐deposited AlN/Si (111) substrates. Nanotemplate selective‐area growth via radiofrequency‐plasma‐assisted molecular beam epitaxy is employed to grow GaN nanocolumns on the nanopillars. Well‐ordered uniform GaN nanocolumn arrays are obtained by inserting a migration‐enhanced‐epitaxy grown AlN/AlGaN buffer layer, thereby aligning the polarity of GaN to Ga‐polar. Subsequently, bulk InGaN active layers are grown on top of the GaN nanocolumns with increasing growth time ( t g = 10–20 min). In the initial stage of growth ( t g = 10 min), low‐In‐content InGaN grows on the edges of the six‐sided pyramidal top of the GaN nanocolumns. As the growth progresses, low‐In‐composition InGaN fills the sides between InGaN on the edges, while high‐In‐composition InGaN rapidly grows on the top of the c‐plane nanocolumns. High‐angle annular dark‐field scanning transmission electron microscopy reveals the formation of an InGaN core, covered with a low‐In‐composition InGaN shell, on the top of the nanocolumns. At t g = 20 min, the photoluminescence spectrum exhibits a peak at 669 nm with a full width at half maximum value of 51.7 nm. Thus, the proposed method is suitable for growing red‐light‐emitting well‐ordered InGaN/GaN nanocolumn arrays on Si.