| Over the last few years the availability of nonpolar/semipolar bulk GaN substrates has spurred intense research efforts towards the realization of novel GaN-based optoelectronic devices. Growth of (Al,In,Ga)N heterostructures on non-basal planes of wurtzite GaN leads to reduced/absent polarization-related internal electric fields and consequently, offers the possibility of improved device performance.;This dissertation focuses on epitaxial growth and characterization of laser diode (LD) structures grown on semipolar GaN. Various semipolar crystal planes were investigated with regards to device design constraints and suitability for high quality epitaxial growth and good device performance. The first electrically-injected semipolar InGaN/GaN LDs were demonstrated on (10-1-1) GaN. Optically pumped lasing in the green spectral region was demonstrated on LD structures grown on (11-22) GaN. Misfit stress relaxation via misfit dislocation (MD) generation was observed in hetero-epitaxially grown semipolar (Al,In)GaN layers. The presence of resolved shear stress on the basal c-plane for semipolar (Al,In)GaN heteroepitaxy limits the critical thickness of AlGaN-cladding and InGaN waveguiding layers, thereby constraining LD device design space. Finally, electrically injected LDs employing the AlGaN-cladding layer free waveguide design were demonstrated on semipolar (20-21) GaN. A maximum lasing wavelength of 506.4 nm was achieved under pulsed operation. |
