Green Emitting Cubic GaInN/GaN Quantum Well Stripes on Micropatterned Si(001) and Their Strain Analysis

GaInN/GaN heterostructures in the cubic lattice variant have the potential to overcome the limitations of wurtzite structures as commonly used for light emitting and laser diodes. Wurtzite GaInN (0001), suffers from large internal polarization fields, which force design compromises toward ultranarrow quantum wells and reduce recombination volume and efficiency, particularly in the green, yellow, and red visible spectral regions. Cubic GaInN microstripes on micropatterned Si(001), with {111} V-grooves oriented along Si 011¯, offer a system free of internal polarization fields, wider quantum wells, and a smaller bandgap energy. 6 and 9 nm Ga1-xInxN/GaN single quantum well structures are prepared and their emission spectra found to be dominated by the recombination in the cubic wells. The peak wavelength ranges from 520 to 570 nm with a polarization predominately perpendicular to the grooves. These values are about 26 nm longer in wavelength than the equivalent wurtzite (11¯01) sample portions and 40 nm longer than the wurtzite (0001) oriented portions. An alloy composition range of 0.2 < x < 0.3 has been estimated in those cubic portions and quantum efficiency comparable to planar wurtzite structures. The stripe geometry and photon polarization may be suitable for optical mode confinement and reduced threshold stimulated emission.