The optical and electrical properties of infrared photodiodes diodes based on InAs/(GaIn)Sb superlattices grown by molecular beam epitaxy were investigated. The diodes, with a cut-off wavelength around 8 µm show a current responsivity of 2 A/W. By proper adjustment of the p-doping level above the n-background concentration the depletion width exceeds a critical size of about 60 nm, leading to the suppression of band-to-band tunneling currents. Above that critical width the dynamic impedance R0A at 77 K reaches values above 1 kV cm2 leading to a Johnson-noise-limited detectivity in excess of 1X10(12) cm/Hz/W

No abstract

Trap centers with an energy level positioned 1/3 of the band gap below the effective conduction band edge are observed in the electroluminescence spectra of InAs/(Galn)Sb superlattice photodiodes with a cutoff wavelength of 11 µm. The trap centers are recognized by simulating the low-temperature current-voltage characteristics of the diodes. Excellent quantitative agreement on both, the l- V characteristic and the differential resistance between the experimental data and the theoretical prediction is achieved. The quantitative simulation of the I- V characteristics shows, that the 77 K performance of InAs/(Galn)Sb photodiodes is dominated by generation-recombination processes even at long wavelengths. Above 50 K, tunneling currents are not of importance

This review aims to provide researchers and managers interested in supply networks with a strategic review of this rapidly expanding field. It does not attempt a comprehensive review of the enormous and fast growing literature but does present the breadth and depth of research and practice in the area. The central aspect of the paper is to suggest that the field can be viewed from four perspectives which all researchers and managers implicitly or explicitly use: upstream, as purchaser; downstream, as supplier; static network, as an auditor of position within its supply network, typically comprising several supply chains, providing a static and comparative view; and dynamic network, as strategist, seeking opportunities to improve the firm's position in an existing network or creating a new network, providing a strategic, dynamic and long-term view.

An approach for the passivation of photodiodes based on compounds of the InAs∕GaSb∕AlSb materials family is presented. The passivation is realized by the overgrowth of patterned mesa devices with a quaternary AlxGa1−xAsySb1−y layer, lattice matched to the GaSb substrate. Proof of concept is demonstrated on infrared photodiodes based on InAs∕(GaIn)Sb superlattices with 10μm cutoff wavelength operating at 77 K where suppression of surface leakage currents is observed.

We have studied InAs/GaSb superlattices (SLs) grown with either InSb-like or GaAs-like interfaces (IFs) on top of a GaSb buffer layer on (100) GaAs substrates. The InAs layer thickness was varied from 4 to 14 monolayers (ML) while the GaSb layer thickness was kept fixed at 10 ML. The type of IF bonds realized was verified by Raman scattering from mechanical IF modes. High-resolution X-ray diffraction using one- and two-dimensional mapping of symmetric and asymmetric reflections allowed us to determine independently the lattice parameters parallel and perpendicular to the growth direction. The GaSb buffer layer was found to be fully relaxed whereas the SLs with InSb-like IFs were coherently strained to the in-plane lattice parameter of the GaSb buffer for InAs layer thicknesses exceeding 6 ML. The strain distribution within the SLs with GaAs-like IFs was obtained from simulations of the X-ray reflection profiles. The SLs were found to be coherently strained close to the GaSb buffer and showed increasing strain relaxation with increasing distance from the buffer layer. In addition, these simulations provide an accurate determination of the SL periods. Well-resolved Raman spectra of backfolded longitudinal acoustic (LA) phonons were observed showing for SLs with ZnSb-like IFs folded LA phonon lines up to the seventh order. The spectrum of quasiconfined optical SL phonons was examined by Raman spectroscopy and by IR reflection. A detailed analysis of the IR reflection spectra allowed an independent determination of the individual layer widths within the SL stack, including the spatial extent of the GaAs-like IF mode

No abstract

We report on GaSb-based 2.Xμm diode lasers with an improved waveguide design, leading to a reduced beam divergence in the fast axis of 44° full width at half maximum (FWHM), compared to 67° FWHM of a conventional broadened waveguide design. 2.3μm ridge-waveguide lasers with the improved epitaxial design showed, besides the narrow beam profile in the fast axis, an excellent slow axis beam quality [M2<1.1 up to 70mW, continuous wave (cw)]. 2.0μm broad-area lasers with the improved waveguide too, exhibit a maximum cw-output power of 1.96W.