Cross-sectional scanning tunneling microscopy of GaAsSb/GaAs quantum well structures

Abstract

We have used cross-sectional scanning tunneling microscopy (STM) to perform nanometer-scale characterization of compositional structure and interfacial properties within GaAs1−xSbx/GaAs double-quantum well structures. An algorithm has been devised based on analysis of strain effects in STM data to obtain detailed, quantitative compositional profiles within alloy layers. Using this and other analysis techniques, we have assessed the influence of group V anion soaks at each heterojunction interface on interface roughness and abruptness. An As soak at the GaAs–on–GaAs1−xSbx interfaces reduces interface roughness but leads to a slight loss of abruptness at the interface, while an As+Sb soak at GaAs1−xSbx–on–GaAs interfaces improves abruptness while leaving interface roughness largely unaffected. Significant compositional grading at the nanometer scale is observed within the GaAs1−xSbx layers.