In0.68Ga0.32As/Al0.64In0.36As/InP 4.5 mu m quantum cascade lasers grown by solid phosphorus molecular beam epitaxy

The authors report the growth and fabrication of 4.5 mu m quantum cascade lasers based on strain balanced In0.68Ga0.32As/Al0.64In0.36As heterostructures by molecilar beam e. pitaxy. A device with 12.5 Arn waveguide width and 2.25 mm cavity length has a threshold curient density of 5 kA/cm(2) and can deliver power from one facet of about 90 mW at room temperature under pulse mode. The characteristic temperature is 124 K. The measured waveguide losses at room temperature are 11.5 and 13.2 cm(-1) with ridae width of 14 and 11 mu m, respectively. The temperature dependence of the waveguide loss is correlated with the change of the carrier mobility. (c) 2007 American Vacuum Society.