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The paper presents a theoretical study of the modulation instability of a continuous or quasicontinuous optical probe in a three level quantum well system under electromagnetically induced transparency. The modulation instability is affected by the control field detuning, as well as even-order dispersion and by the strength of Kerr (third-order) and quintic (fifth-order) nonlinearities. The fourth-order dispersion reduces the bandwidth over which modulation instability occurs, whereas the quintic nonlinearity saturates the growth of the modulation instability. Detuning the control field from resonance can significantly reduce the growth of the modulation instability at both low and high power levels. At low powers, the system becomes stable against modulation instability for small detuning of the control field and at high powers modulation instability disappears for larger detuning. [ABSTRACT FROM AUTHOR]

Superconductivity in topological materials has attracted a great deal of interest in both electron physics and material sciences since the theoretical predictions that Majorana fermions can be realized in topological superconductors. Topological superconductivity could be realized in a type II, band-inverted, InAs/GaSb quantum well if it is in proximity to a conventional superconductor. Here, we report observations of the proximity effect induced giant supercurrent states in an InAs/ GaSb bilayer system that is sandwiched between two superconducting tantalum electrodes to form a superconductor-InAs/GaSb-superconductor junction. Electron transport results show that the supercurrent states can be preserved in a surprisingly large temperature-magnetic field (T – H) parameter space. In addition, the evolution of differential resistance in T and H reveals an interesting superconducting gap structure. [ABSTRACT FROM AUTHOR]

Temperature-dependent measurements of carrier recombination rates using a time-resolved optical pump-probe technique are reported for mid-wave infrared InAs/InAs1–xSbx type-2 superlattices (T2SLs). By engineering the layer widths and alloy compositions, a 16K band-gap of ~235±10 meV was achieved for five unintentionally and four intentionally doped T2SLs. Carrier lifetimes were determined by fitting lifetime models based on Shockley-Read-Hall (SRH), radiative, and Auger recombination processes to the temperature and excess carrier density dependent data. The minority carrier (MC), radiative, and Auger lifetimes were observed to generally increase with increasing antimony content and decreasing layer thickness for the unintentionally doped T2SLs. The MC lifetime is limited by SRH processes at temperatures below 200K in the unintentionally doped T2SLs. The extracted SRH defect energy levels were found to be near mid-bandgap. Also, it is observed that the MC lifetime is limited by Auger recombination in the intentionally doped T2SLs with doping levels greater than n~1016 cm–3. [ABSTRACT FROM AUTHOR]

Interband-cascade infrared photodetectors (ICIPs), composed of discrete superlattice absorbers, are demonstrated at temperatures up to 350 K with a cutoff wavelength near 5 μm at 80 K to beyond 7 μm above room temperature. The peak responsivity exceeds 200 mA/W, higher than the values reported from early interband cascade laser structures, suggesting a significantly enhanced quantum efficiency of the superlattice absorbers. A theoretical model, originally developed for quantum well infrared photodetectors (QWIPs), is applied to ICIPs to analyze their device performance. The Johnson-limited and background-limited detectivities are extracted and indicate that background-limited performance temperatures for two ICIP structures are 126 and 105 K at 5 μm. It is expected that optimized ICIPs will provide improved performance by combining the advantages of conventional photodiodes and the discrete nature of QWIPs and IC lasers. [ABSTRACT FROM AUTHOR]

We have used cross-sectional scanning tunneling microscopy (STM) to perform nanometer-scale characterization of compositional structure and interfacial properties within GaAs[sub 1-x]Sb[sub x]/GaAs double-quantum well structures. An algorithm has been devised based on analysis of strain effects in STM data to obtain detailed, quantitative compositional profiles within alloy layers. Using this and other analysis techniques, we have assessed the influence of group V anion soaks at each heterojunction interface on interface roughness and abruptness. An As soak at the GaAs-onGaAs[sub 1-x]Sb[sub x] interfaces reduces interface roughness but leads to a slight loss of abruptness at the interface, while an As+ Sb soak at GaAs[sub 1-x]Sb[sub x]-on-GaAs interfaces improves abruptness while leaving interface roughness largely unaffected. Significant compositional grading at the nanometer scale is observed within the GaAs[sub 1-x]Sb[sub x] layers. [ABSTRACT FROM AUTHOR]

Provides information on the characterization of strained aluminum gallium arsenide/indium gallium arsenide/gallium arsenide quantum-well structures bonded directly to glass or silicon dioxide-coated silicon substrates. Preparation of glass slides or silicon dioxide-coated silicon substrates; Thermal expansion characteristics of the bonded layer; Description of low-temperature photoluminiscence measurements.

Presents a study that investigated silicon (Si)-implant activation characteristics in Al[subx]Ga[sub1-x]As for aluminum compositions of 0%-70% AlAs for doses of 5.6x10[sup12] and 2.8x10[sup13] cm[sup-2] at 100 KeV. Analysis of the effective activation efficiency; Compositional dependence of the ionization energy and conduction band density-of-states of AlGaAs; Discussion on the effects of phosphorus coimplantation.

Presents information on a study which investigated the p-type ion-implantation doping of aluminum[sub0.75] gallium[sub0.25] antimony. Experimental procedure; Results; Discussion.