Atomic Force Microscopy and Spectroscopy of Self-Assembled InAsSb Quantum Dots grown on InP Substrates by MOCVD

Abstract

ABSTRACTInAsSb quantum dot (QD) lasers are promising light sources with emission wavelengths beyond 2μm as recently demonstrated. We report the first detailed atomic force microscope (AFM) characterization of uncapped InAsSb quantum dots self-assembled on GaAs/In0.53Ga0.47As layers. These quantum dot structures are grown on (100) InP substrates by metal organic chemical vapor deposition (MOCVD). Growth conditions are chosen to maximize photoluminescence intensity and to obtain high output powers from Fabry-Perot lasers with one stack of InAsSb QDs. Conductive AFM is employed to simultaneously study topography, current image, and current-voltage (I-V) characteristics from various InAs1-ySby QDs with y varied between 0 and 0.25. Typical dot density is 4–5×1010/cm2 and dots are estimated to have a lateral dimension at the base of ∼40nm and a height of 2–5nm. I-V characteristics measured from individual InAsSb QDs are compared to those from InAs QDs. Also reported are electronic properties including energy band gaps of InAs and InAsSb QDs.