Freestanding GaN slab fabricated on patterned silicon on an insulator substrate

We propose the growth of GaN on patterned silicon-on-insulator (SOI) substrates, i.e. the GaN-on-patterned-SOI technique. The selective growth is suppressed at the low temperature molecular beam epitaxy (MBE) growth, and GaN nanocolumn are thus epitaxially grown on a silicon substrate and a silicon oxide substrate. The GaN slabs grown on the silicon oxide substrate are totally suspended in space by an association of bulk silicon micromachining and buffered HF etching. The photoluminescence and the reflection results suggest that silicon absorption of the emitted light is eliminated for the freestanding GaN slab, and the reflection losses are reduced at the GaN nanocolumn surface. This work provides a promising way to combine SOI technology with the growth of GaN for producing new optical devices.