On the structural characterization of InAs/GaSb type-II superlattices: The effect of interfaces for fixed layer thicknesses

Structural and optical characterization of InAs/GaSb type-II superlattices: Influence of the change in InAs and GaSb layer thicknesses for fixed InSb-like interfaces

“…It was shown in Ref. [16] that the change in the band gap of the superlattice structures having almost the same period thickness followed the change in the strain. Namely, the decrease in the tensile strain reduced the band gap and therefore red shifted the cut-off wavelength.…”

“…The selected V/III beam equivalent pressure ratios were around 8 for GaSb, 7 for InAs layers in the SL and 4 for InAs cap layer. InAs and GaSb layer thicknesses were defined from growth rates which were calibrated by using high resolution transmission electron microscopy and high resolution X-ray diffraction (HRXRD) [16]. For HRXRD measurements PANalytical X'Pert Pro MRD HRXRD system was used and all measurements were performed around GaSb (0 0 4) symmetry axis with 0.0005°precision by using Cu Kα 1 radiation (λ = 0.15406 nm).…”

“…The SL region consists of 40-periods p-type, 60-periods undoped and 40-periods n-type InAs/GaSb SL layers with InSb-like strain balancing interfaces. The same interface recipes (i.e., shutter sequences and timing) for GaSb → InAs and for InAs → GaSb transitions were used in all consecutively grown samples [16].…”

“…InSb-like interface formations which introduce a compressive strain on SL structure are widely used between the SL layers in order to compensate this structural strain [14,15]. Behavior of the perpendicular lattice mismatch (Δa ⊥ /a) due to the InSb-like interface thickness for fixed InAs (9 ML) and GaSb (9 ML) layer thicknesses was published elsewhere [16]. Therefore, for strain and band gap engineering, the individual InAs and GaSb layer thicknesses in each period need to be considered as control parameters when designing a new SL structure.…”

InAs/GaSb Type-II Superlattice Detectors

“…Since performance of T2SL device is strongly dependent on T2SL structural perfection, the information on interfacial roughness, compositional profile (i.e., interfacial intermixing), and interfacial bonding across the noncommon anion layers of InAs/GaSb T2SL is very important. Growth conditions of T2SLs have been optimized by various research groups to improve the interface quality [50][51][52][53][54]. Steinshnider and colleagues [55][56][57][58] utilized the cross-sectional scanning tunneling microscopy (XSTM) to identify the interfacial bonding and to facilitate direct measurements of the compositional grading at the GaSb/InAs heterojunction.…”