Growth, Fabrication, and Characterization of Continuous-Wave Aluminum Gallium Nitride -Cladding-Free m-plane Indium Gallium Nitride / Gallium Nitride Laser Diodes

Many applications exist for InGaN/GaN laser diodes (LDs), including high-density optical data storage, laser-based projection displays, high-resolution laser printing, solid-state lighting, medical diagnostics, and chemical sensing. Although device performance continues to improve, current commercially-available InGaN/GaN LDs are still grown on the (0001) c-plane of the wurtzite crystal structure and their performance is nonetheless affected by the presence of polarization-related electric fields.;As an alternative to conventional c-plane technologies, growth of InGaN/GaN LDs on nonpolar or semipolar orientations presents a viable approach to reducing or eliminating the issues associated with polarization-related electric fields. Despite these potential advantages, though, the lowest reported threshold current densities for nonpolar and semipolar LDs are still about 2 to 3 times higher than those reported for c-plane LDs. In this thesis, we discuss the growth, fabrication, and characterization of continuous-wave AlGaN-cladding-free (ACF) m-plane LDs with performance that is comparable to the best state-of-the-art c-plane LDs.;In the first part of this thesis, the characterization of low-defect-density m-plane thin films and devices grown by metalorganic chemical vapor deposition is presented. The physical origin of the four-sided pyramidal hillocks commonly observed on m-plane thin films is identified and an understanding of these mechanisms is used to explain the impact of carrier gas and substrate misorientation on the morphological, structural, and optical properties of m-plane thin films and devices. In the second part of this thesis, several aspects of the development of a quick, self-aligned LD fabrication process are discussed. These include the implementation of relatively conventional fabrication technologies for routine device processing as well as the development of innovative approaches for improving the accuracy and reproducibility of facet cleaving and ridge waveguide etching processes. Finally, in the third and last part of this thesis, the performance of ACF m-plane LDs with threshold current densities of 1.54 kA/cm2 and peak output powers of 1.6 W is discussed. The transparency carrier density of these devices is estimated to be 4.9 x 10 18 cm-3, which is lower than typical transparency carrier densities reported or even calculated for c-plane GaN-based LDs and comparable to typical transparency carrier densities reported for GaAs- and InP-based LDs.