Stress Engineering for Semipolar (2021) Blue and Green InGaN Based Laser Diodes

High performance InGaN-based green laser diodes (LDs) will enable new laser-based display application. Semipolar (2021) offers advantages over conventional c-plane grown LDs in terms of reduced polarization related electric fields and higher differential gain. One of many challenges towards improving green LDs is the decrease in optical confinement factor (OCF) with lasing wavelength due to index dispersion. Relaxation of misfit strain via bend and glide of pre-existing threading dislocations (TDs) limits (2021) oriented LDs to lower waveguiding/cladding thickness relative to c-plane. Understanding and managing strain relaxation in semipolar GaN-based heterostructures is critical to the development of high performance semipolar oriented LDs.;To establish a platform for studying stress management on (20 21) oriented LDs, coherent green LDs are developed. The link between post-QW annealing effects and the size of dark triangle defects is clarified and used to demonstrate 511 nm LDs with GaN barriers, having threshold current density (Jth) of 15 kA/cm-2. Additionally, the first true-green ITO-clad LD with a lasing wavelength of 518 nm is demonstrated. Secondary relaxation on inclined m-planes is observed, identified and linked to TD generation. Si and Mg doping is shown to significantly alter semipolar relaxation by suppressing m-plane slip significantly more than c-plane slip. 2D relaxation was investigated via thick, graded composition buffers and stripe patterning based elastic relaxation, but was always accompanied by TD generation in the mid 108--10 9 cm-2.;Metamorphic LDs are developed utilizing 1D relaxed n-InGaN layers as the lower waveguide in GaN-clad LD structures. Hole blocking layers are found to significantly suppress MD related non-radiative losses. Blue LDs with Jth as low as 4 kA/cm-2 are demonstrated.;Patterning mesas into the substrate before growth, known as limited area epitaxy (LAE), is shown to block TD glide. Using LAE, InGaN and AlGaN layers having thicknesses 5--7 times greater than their theoretical critical thickness are grown without significant MD formation. High performance blue and green LAE LDs having an OCF as much as two times greater than standard planar LDs are demonstrated at 456 nm with Jth of 4.5 kA/cm2 and at 523 nm with Jth of 12 kA/cm2.