Semi-polar {1 0 1} blue and green InGaN/GaN light-emitting diodes on micro-stripe patterned Si (1 0 0)

Abstract

A novel III-nitride-based light emitting diode (LED) fabrication process which is based on selective-area epitaxial growth on Si {1 1 1} facets etched into Si (1 0 0) substrates is presented. A micro-stripe pattern is formed with semi-polar {1 0 1} crystallographic planes of GaN evolving from an epitaxial lateral overgrowth (ELOG)-like process. The {1 0 1} planes of GaN serve as a template for the growth of semi-polar blue and green LED structures with InGaN/GaN multiple quantum wells (MQW). A complete fabrication chain encompassing substrate etching, metalorganic vapor phase epitaxy (MOVPE), characterization, LED processing and device manufacture has been developed.The semi-polar LED stacks are of high crystalline quality, which is manifested by homogeneous InGaN layers in the {1 0 1} MQW structure and smooth {1 0 1} LED surface planes. Although threading dislocations intersect with the semi-polar {1 0 1} MQW, V-shaped defects typically observed in polar c-plane MQW structures are not detected.The blue and green semi-polar LED show only a weak polarization-related wavelength shift at large current densities consistent with the lower built-in electric fields in the semi-polar MQW. At low current densities, the green LED exhibit a strong wavelength shift due to In clustering effects. The blue LED reveal a stable emission color, which indicates a homogeneous In distribution in the wells.