Catalytic nanocapillary condensation and epitaxial GaN nanorod growth

Abstract

Intrinsic catalytic process by capillary condensation of Ga atoms into nanotrenches, formed among impinging islands during the wurzite-GaN thin film deposition, is shown to be an effective path to growing GaN nanorods without metal catalysts. The nanocapillary brings within it a huge imbalance in equilibrium partial pressure of Ga relative to the growth ambient. GaN nanorods thus always grow out of a holding nanotrench and conform to the boundaries of surrounding islands. The nanorods are epitaxially orientated with ${⟨0001⟩}_{\mathrm{Ga}\mathrm{N}}\ensuremath{\Vert}{⟨111⟩}_{\mathrm{Si}}$ and ${⟨2\underset{̱}{11}0⟩}_{\mathrm{Ga}\mathrm{N}}\ensuremath{\Vert}{⟨110⟩}_{\mathrm{Si}}$ similar to the matrix. Concaved geometry is essential and is a condition that limits the axial dimension of the nanorods protruding above the base (matrix) material region. Revelation of the growth mechanism in the current context suggests that fabrication of nanoquantum structures with controlled patterns is enabling for any attainable dimensions.