Pure Blue Laser Diodes Based on Nonpolar m-Plane Gallium Nitride with InGaN Waveguiding Layers

Abstract

Blue laser diodes (LDs) based on m-plane gallium nitride were demonstrated by using m-plane GaN substrates. The lasing wavelength and the threshold current under pulsed operation were 451.8 nm and 134 mA (22.3 kA/cm²), respectively. The device structures consisted of InGaN-based multi-quantum wells, InGaN guiding layers, and Al-containing cladding layers. The InGaN guiding layers play two roles; as appropriate optical waveguides for longer lasing wavelengths and for the prevention of macroscopic cracks parallel to the c-plane. The latter is an indispensable technology in order to fabricate nonpolar LDs for longer wavelengths beyond the blue region.