Preparation of a strip structure for quantum-cascade lasers

A method for overgrowing laser stripe structures with high-ohmic indium phosphide to bound the domain of current flow and to improve heat dissipation is presented. Overgrowing was performed using metal-organic chemical-vapor deposition. It is shown that the method makes it possible to obtain high-quality epitaxial layers and defectless overgrowth boundaries without special processing of the structures after photolithography. All the InP layers were n-conductive, the specific resistance was $\rho\sim$ 5 $\times$ 10$^4$ $\Omega$ cm, and the carrier concentration was $n\sim$ 5 $\times$ 10$^{10}$ cm$^{-3}$. The characteristics of the grown InP layers permit one to obtain high-quality quantum-cascade lasers.