Crack-free GaN grown on AlGaN∕(111)Si micropillar array fabricated by polystyrene microsphere lithography

The authors report on the growth of GaN on AlGaN∕(111)Si micropillar array by metal-organic chemical vapor deposition. Using the substrates with micropillar array, 2-μm-thick GaN films without cracks can be achieved. Transmission electron microscopy, atomic force microscopy, and micro-Raman studies indicate that the dislocation density and residual stress of the GaN grown on micropillar array are also reduced. The results reveal the potential of this type of substrates for growing GaN-based devices as well as preparing GaN freestanding substrates.