Band lineup of pseudomorphic GaAs_(1-x)Sb_x quantum-well structures with GaAs, GaAsP, and InGaP barriers grown by metal organic chemical vapor deposition

摘要

We report the growth of thin pseudomorphic GaAs_(1-x)Sb_x (x ～ 0.3) quantum-well heterostructures by metal-organic chemical vapor deposition and the measurement of the band lineups for the heterointerface of GaAs_(1-x)Sb_x (x～0.3) quantum wells with GaAs, GaAs_(0.86)P_(0.14), and In_(0.5)Ga_(0.5)P quantum-well barriers for 80 A double-quantum-well heterostructures using excitation-dependent cathodoluminescence measurements at 10 K. GaAs_(1-x)Sb_x (x～0.3) quantum wells with GaAs and GaAs_(0.86)P_(0.14) barriers show type-Ⅱ band alignment, while GaAs_(1-x)Sb_x (x ～ 0.3) quantum wells with In_(0.5)Ga_(0.5)P barriers exhibit a type-Ⅰ band lineup. The type-Ⅰ/type-Ⅱ band alignment boundary condition as a function of the GaAs_(1-x)Sb_x quantum-well composition and of the barrier materials and compositions is calculated. The pseudomorphic GaAs_(1-x)Sb_x/GaAs quantum-well heterointerface is estimated to have a type-Ⅱ alignment. For GaAs_(1-x)Sb_x/GaAsP and GaAs_(1-x)Sb_x/InGaP heterostructures, both type-Ⅰ and type-Ⅱ alignments can occur depending on the quantum-well and barrier compositions. As the Sb composition of the quantum well increases, higher P alloy composition (in GaAsP barriers) and Ga (in InGaP barriers) composition are required in order to make the type-Ⅱ to type-Ⅰ transition.