Structural and transport properties of InAs/AlSb superlattices

We report the demonstration of molecular beam epitaxy (MBE) grown InAs/AlSb superlattices with properties suitable for cladding layer materials in semiconductor diode lasers operating in the 2–5 μm spectral range. X-ray rocking curves of these superlattices reveal excellent structural quality and small lattice mismatch (Δa/a = 1.2 × 10⁻³) with respect to a GaSb substrate. Hall measurements reveal that controllable n-type doping of InAs/AlSb superlattices can be achieved by selectively codepositing silicon during growth of InAs layers. p-Type doping is performed by codepositing beryllium during growth of AlSb layers. InAs/AlSb superlattice p-n junctions have been fabricated and tested, yielding classical p-n diode current-voltage behavior. A simple double heterojunction diode laser, incorporating InAs/AlSb superlattice cladding layers and a Ga_xIn₁−xAs_ySb₁−y active layer, is demonstrated. The emission wavelength of the laser is 2.42 μm (2.50 μm) at 95 K (180 K).