Selective modification of the band gaps of GaInNas/GaAs structures by quantum well intermixing techniques

Abstract

We report the unambiguous demonstration of controlled quantum well intermixing (QWI) in the technologically important GaInNAs/GaAs 1.3 μm material system. QWI is a key technique to selectively modify the band gap of quantum wells, which has found broad application in semiconductor lasers and photonic integrated circuits (PICs). Extending such technology to GaInNAs/GaAs structures is highly desirable due to the technologically advantageous properties of this material system. Here, we investigate well-characterized GaInNAs quantum well material which has been annealed “to saturation” before QWI processing to allow unambiguous interpretation of results. After RTA at 700 °C for ∼180 s, controlled shifts in band-gap at room temperature of up to 200 nm have been observed in sputtered SiO 2-capped samples, whilst uncapped and PECVD SiO 2-capped samples demonstrated negligible shift. This selective modification of the band gap has been confirmed by detailed photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy. Analysis of composition profile by SIMS revealed that the QWI is due to the interdiffusion of In–Ga between the quantum wells and the barriers enhanced by the point defects generated during the sputtering process. Investigation of a series of samples of differing N concentrations will be presented, which provides extra information about the intrinsic properties of GaInNAs.