Low dislocation density, high power InGaN laser diodes

Abstract

We used single crystals of GaN, obtained from high-pressure synthesis, as substrates for Metalorganics Vapor Phase Epitaxy growth of violet and UV laser diodes. The use of high-quality bulk GaN leads to the decrease of the dislocation density to the low level of 105 cm−2, i.e. two orders of magnitude better than typical for the Epitaxial Lateral Overgrowth laser structures fabricated on sapphire. The low density and homogeneous distribution of defects in our structures enables the realization of broad stripe laser diodes. We demonstrate that our laser diodes, having 15 μm wide stripes, are able to emit 1.3-1.9 W per facet (50% reflectivity) in 30 ns long pulses. This result, which is among the best ever reported for nitride lasers, opens the path for the development of a new generation of high power laser diodes.

Properties of InGaN blue laser diodes grown on bulk GaN substrates

“…We grow our GaN/AlGaN/InGaN laser structures in a home-made vertical flow MOVPE reactor using TMGa, TEGa, TMAl, TMIn, CP 2 Mg, SiH 4 and ammonia as precursors [9,10]. The growth is monitored in-situ by laser-reflectometry.…”

Seeded growth of GaN single crystals from solution at near atmospheric pressure

“…from solution. Growth from the liquid phase has resulted in GaN single crystals with dislocation densities less than 10 2 cm À2 [7]. High-pressure nitrogen solution growth (HPS) method is carried out using high pressures (greater than 1.0 GPa) and high temperatures (greater than 1400 1C) to dissolve nitrogen into Ga and has been successfully used to grow thin GaN crystal platelets of up to 1.5 cm, laterally [8].…”

Defects in GaN single crystals and homoepitaxial structures

“…Assuming the device structure similar to that shown in Ref. [23], these are: (i) growth of InGaN compliance, (ii) AlGaN:Mg electron blocking and (iii) AlGaN:Mg cladding layers. Selective etching of the full laser structure reveals individual and clustered dislocations emerging at the device surface, as shown in Fig.…”