Buried heterostructure (BH)-QCLs using insulating material that BIBW2992 is epitaxially overgrown over the etched laser stripes provide the best heat extraction from the active region. Insulating iron-doped indium-phosphide (InP:Fe) can be overgrown with a high interface quality by GSMBE at approximately the same growth temperatures as the primary wafer growth, thus avoiding thermal relaxation of the highly strained AlAs barriers ,  and . Continuous-wave (cw) operation, which is an essential performance aspect for the broadening of QCL applications, was demonstrated up to a temperature of 210 K with thin epi-down-mounted narrow (7μm-wide) QCL stripes using InP:Fe as lateral cladding .
In the previous studies we improved heat extraction capabilities of InP:Fe-covered BH-QCLs using a thin (20 nm) InAlAs spacer layer between the laser ridge sidewalls and the InP:Fe insulating layers. This led furthermore to a clear improvement of the crystal quality of the interface, which is telophase otherwise populated by void-like defects playing against an efficient heat extraction out of the laser core .