Pendeo-epitaxy: A new approach for lateral growth of gallium nitride films

Lateral growth of gallium nitride (GaN) films having a low density of dislo cations and suspended from side walls of [0001] oriented GaN columns and ov er adjacent etched wells has been achieved without the use of, or contact w ith, a supporting mask or substrate. Pendeo-epitaxy is proposed as the desc riptive term for this growth technique. Selective growth was achieved using process parameters that promote lateral growth of the {<11(2)over bar 0>} planes of GaN and disallow nucleation of this phase on the exposed silicon carbide substrate. The large horizontal/vertical growth rate ratio indicate that the diffusion distances and the rates of diffusion of the reactant sp ecies along the(0001) surfaces were sufficient to allow them to reach and m ove along the {<11(2)over bar 0>} surfaces before they were chemically adso rbed. A four-to-five order decrease in the dislocation density was observed via transmission electron microscopy in the free-standing laterally grown GaN relative to that in the GaN columns. Curvature of the {<11(2)over bar 0 >} planes as they approached coalescence, and elongated voids below the reg ions of coalescence were formed. The use of optimized growth conditions or more closely spaced columns should eliminate these voids.