Embedded voids formation by overgrowth on GaN nanowires for high-quality GaN films

Overgrowth of GaN on GaN nanowires produced by mask-less etching

“…The exact process and recipe has been reported elsewhere [10,11]. The 1st generation of overgrown GaN EVA film is then put through another process of EVA overgrowth using it as a template material to be etched.…”

“…This EVA technique is capable of reducing the dislocation density (in our films) from 10 9 /cm À 2 by two orders of magnitudes; achieving dislocation densities in the 10 7 /cm À 2 range [10,11]. EVA is based on the overgrowth of GaN on GaN nanowires.…”

“…thick) were grown on (0001) sapphire substrates, and then etched in a Trion Minilock system by the Inductively-coupled Plasma Reactive Ion-Etching (ICP-RIE) technique to obtain nanowires. For GaN etching, a gas mixture of Cl 2 (27 sccm) and BCl 3 (5 sccm) have been used with ICP/RIE powers of 300/100 W respectively at a pressure of 2 Pa. Overgrowth by EVA was carried out again using MOCVD and these procedures have been reported elsewhere [10,11]. High Resolution Scanning Electron Microscopy (HRSEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) were used for the characterization of the initial films and the etched nanowires as well as for the overgrown films.…”

Growth behavior of GaN epilayers on Si(111) grown by GaN nanowires assisted epitaxial lateral overgrowth

“…15,16 Recently, one-dimensional (1D) nanostructures such as nanowires (NWs), nanocolumns and nanorods have been conveniently used as the templates for growing GaN epilayers. [17][18][19][20][21][22][23] Li et al have reported the successful growth of low-dislocation density nonpolar a-plane GaN on a sapphire substrate by using nanowire-templated lateral epitaxial overgrowth. 17 Recently, Dogan et al have reported the GaN NWs template for the pendeo-epitaxial coalescence overgrowth of GaN epilayers on Si(111) by molecular beam epitaxy (MBE).…”

“…18 Embedded voids approach (EVA) was utilized to grow high-quality GaN films on GaN NWs by using metalorganic chemical vapor deposition (MOCVD). 19 In another study, Kim et al have reported the growth of thick single crystalline ZnO films by employing a ZnO nanorodassisted epitaxial lateral overgrowth process. 20 These growth techniques involve an array of vertically aligned, defect-free GaN NWs via a metal catalyst vapor-liquid-solid (VLS) method followed by the growth of coalesced GaN epilayers on the top of the GaN NWs.…”