SINCRONE

The current interest in wide band gap semiconductors (e.g. GaN and ZnO) is motivated by their superior properties in fields as diverse as optoelectronics and nanoelectronics. However their development is still plagued by the high density of structural defects resulting from the lack of adapted/low cost substrates. The problem of structural quality can be overcome by a bottom-up approach consisting in nanowire structures, with virtually perfect structural properties. However the state of the art of nanowire growth, i.e. random nucleation and size inhomogeneities of wires, does not make them suitable for large scale applications. Then, the next challenge will be the in-plane organization of nanowire. In this project, we will combine the excellent properties of nanowires and of nanowire heterostructures with the use of nanopatterned substrates permitting selective area growth (SAG) in mask apertures and controlled in-plane ordering of the nanostructures. To achieve selective growth at large scale, high definition and high throughput, eventually leading to low cost, we choose nanoimprint lithography (NIL) as nanopatterning technology. In addition, the specific choice of silicon as a base for nanopatterned substrates will open the way to integrated optoelectronics while offering an access to microlectronics mainstream tools. A special interest will be paid to the development of NIL technology on flexible silicon substrates. The SINCRONE project targets to apply this combination of elemental bricks to a promising disruptive light emitting diode (LED) concept based on vertically aligned nanowire (NW) emitters, and more specifically on organized arrays of such emitters. It offers the potential to address present limitations of the current 2D GaN on sapphire based industrial LED approach. NWs based LEDs offer the unique opportunity to be grown on silicon substrates with defect free structure and obvious cost advantages. Moreover, heavily doped substrates allow vertical injection configuration and simpler integration processes. Silicon also has the advantage of higher thermal conductivity than sapphire. Although self assembly of NWs has been demonstrated, the intrinsic non uniformity of density, diameter, quantum wells (QWs) composition and thickness leads to emission wavelength and emittance spatial variations that limit the scaling up of the NW LEDs technology for lighting. The SINCRONE project brings together the required complementary expertises to produce and fully characterize organized nanostructures arrays: 1) an industrial silicon wafer manufacturer that can customize templates fabrication according to the project specifications ; 2) a laboratory, involved in technological R & D, that is currently developing optoelectronics device design including electromagnetic simulation, NIL as a generic nanopatterning tool and a full GaN or ZnO NW based LEDs route ; 3) a basic research laboratory, involved in growth studies of GaN based nanowires both by MBE and by MOCVD and in optical studies on these nanostructures.