Cubic phase GaN on nano-grooved Si (100) via maskless selective area epitaxy

Abstract

A method of forming cubic phase (zinc blende) GaN (referred as c-GaN) on a CMOS-compatible on-axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h-GaN) and possess very high polarization fields (∼MV/cm) along the common growth direction of <0001>. Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization-free along the common growth direction of <001>, however, this phase is thermodynamically unstable, requiring low-temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano-groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress-free, and low-defectivity c-GaN on CMOS-compatible on-axis Si. These results suggest that epitaxial growth conditions and nano-groove pattern parameters are critical to obtain such high quality c-GaN. InGaN/GaN multi-quantum-well structures grown on c-GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology. Thermodynamically stable, stress-free, and low-defectivity GaN is integrated on CMOS Si (100) substrates. A new mask-free local-area epitaxy is introduced, resolving the issue of lattice and thermal mismatch between GaN and Si. A novel U-shaped nano-groove pattern is proposed, enabling polarization-free cubic phase GaN. InGaN/GaN multi-quantum-well structures on such polarization-free GaN/Si templates offer an ideal roadmap for (integrated) photonic devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.