Nonselective etching of GaAs/AlGaAs double heterostructure laser facets by Cl2 reactive ion etching in a load-locked system

Abstract

Reactive ion etching was used for etching laser facets of GaAs/AlGaAs transverse junction stripe lasers. A new load-locked reactive ion etching system was developed to dramatically reduce the background partial pressure of O2 and H2O in the chamber, substantially reducing the oxidation of AlGaAs and permitting equal rate etching of GaAs and AlGaAs with smooth vertical facets. Etching is performed with a chlorine plasma at a low pressure (0.5 mTorr), and bias voltage (−350 V) at a rate of ∼850 Å/min. This simple, single-step dry etching process is suitable for optoelectronic integration and eliminates the requirement of unreliable wet chemical etching or microcleaving techniques. This new system is used to fabricate transverse junction stripe lasers with facet reflectivities of more than 16%. These high quality dry etched facets result in only a 7.5% increase of the threshold current above that of lasers with cleaved facets.