Relationship between transport properties and band diagrams in InAsxSb1−x/Al0.1In0.9Sb quantum wells

The resistivity of InAs0.1Sb0.9/Al0.1In0.9Sb quantum wells (QWs) is much lower than that of InSb/Al0.1In0.9Sb QWs, staying low resistivity even at low temperature. Fundamental difference in low temperature transport properties between InSb/Al0.1In0.9Sb and InAs0.1Sb0.9/Al0.1In0.9Sb QWs was revealed, based on the band diagram calculations of these QWs. Band diagrams of InAsxSb1−x/Al0.1In0.9Sb QWs showed that the energy band of the InAsxSb1−x layer moves downward with increasing As content x. The QW is type I at x equal to 0, becomes type II at x equal to 0.1. The Fermi level (EF) of the InSb QWs lies in the band gap and below apart from the bottom of the conduction band, while EF of the InAs0.1Sb0.9 QWs is above the bottom of the conduction band of the well. The calculated sheet carrier densities are in good agreement with the experimental results. It well explains that the sheet carrier density difference between InSb and InAs0.1Sb0.9 QWs mainly originates from this band diagram difference and the position of EF.