Suppression of relaxation in (20(2)over-bar1) InGaN/GaN laser diodes using limited area epitaxy

Confinement factor (Gamma) of semipolar (20 (2) over bar1) green laser diodes (LDs) is limited by relaxation of coherency stresses in the waveguiding heterostructure. In this paper, we demonstrate the suppression of relaxation by blocking glide of pre-existing threading dislocations using limited area epitaxy (LAE). With LAE, we show a factor of three increase in thickness before the observation of significant misfit dislocation formation for (20 (2) over bar1) oriented In0.08Ga0.92N/GaN heterostructures. We then apply this technique to fabricate coherent AlGaN-cladding-free LDs with 73% enhanced Gamma relative to planar devices without LAE, having an emission wavelength of 495 nm and threshold current density of 10.7 kA/cm(2). This technique is readily applicable to AlGaN or AlInGaN cladding in addition to InGaN waveguiding layers to improve Gamma of semipolar LDs. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770367]