The 6.1 Å family (InAs, GaSb, AlSb) and its heterostructures: a selective review

The three semiconductors InAs, GaSb, and AlSb form an approximately lattice-matched set around View the MathML source, covering a wide range of energy gaps and other properties. Of particular interest are heterostructures combining InAs with one or both of the antimonides, and they are emphasized in this review. In addition to their use in conventional device types (FETs, RTDs, etc.), several heterostructure configurations with unique properties have been explored, especially InAs/AlSb quantum wells and InAs/GaSb superlattices. InAs/AlSb quantum wells are an ideal medium to study the low-temperature transport properties in InAs itself. With gate-induced electron sheet concentrations on the order View the MathML source, they exhibit a pronounced conductivity quantization. The very deep wells View the MathML source provide excellent electron confinement, and also permit modulation doping up to at least View the MathML source. Because of the very low effective mass in InAs, heavily doped wells are essentially metals, with Fermi energies around View the MathML source, and Fermi velocities exceeding View the MathML source. Contacted with superconducting electrodes, such structures can act as superconductive weak links. InAs/GaSb-related superlattices with their broken-gap lineup behave like semimetals at large lattice periods, but if the lattice period is shortened, increasing quantization effects cause a transition to a narrow-gap semiconductor, making such structures of interest for infrared detectors, often combined with the deliberate addition of strain.