Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 47: GaN: Devices II
HL 47.5: Vortrag
Donnerstag, 30. März 2006, 16:15–16:30, BEY 118
Processing and Characterization of GaN homo-epitaxial Laser Diodes — •Jens Dennemarck, Stephan Figge, and Detlef Hommel — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee NW1, D-28359 Bremen
The threshold of GaN-based laser diodes is mainly determined by the geometry of the ridge wave-guide and its processing. In this work we are investigating different ridge structures to lower the threshold current density. The emission wavelength of the laser diodes, grown homo-epitaxially on GaN substrates with dislocation densities in the range of ≈ 106cm−2, is 395nm.
To improve the device performance, the stripe width of the devices was varied from 2−10µ m and three different depths of the ridge were applied: a planar structure (no ridge), 600nm - starting at the upper wave-guide, and 900nm - penetrating the active region.
The largest impact on the threshold current density was found in the depth of the ridge, where the devices with the largest depth showed a reduction of a factor of 5 to 3kA/cm2 in comparison to the planar structures. Duty cycles up to 50% could be applied an these devices. The width of the ridge showed also a reduction of the threshold, but not as much as the depth.
Additional to this, a better optical confinement for the deepest ridge could be seen in the far field of the laser diode.