A. Jasik

Low-temperature grown near surface semiconductor saturable absorber mirror: Design, growth conditions, characterization, and mode-locked operation

We have developed a mode-locked diode-pumped Yb:KY(WO4)2 laser generating nearly bandwidth limited pulses as short as 101 fs. At 1.1 W of absorbed power and for 3% transmission output coupler, the laser delivers 150 mW in pulses of 110 fs duration, which corresponds to the efficiency of 14%. This has been achieved using semiconductor saturable absorber mirror (SESAM) grown by molecular beam epitaxy. The low-temperature (LT) absorbers were crystallized under the carefully optimized growth conditions. The resonantlike type structures ensured relatively high enhancement factor and in consequence high absorption modulation. The main device parameters such as group delay dispersion (GDD) and enhancement factor were chosen to be wavelength independent. The optimization of the growth conditions resulted in a reduction in the nonsaturable absorption in as-grown LT-InGaAs absorbing layer and ensured the fast carrier trapping and recombination. We assume that the nonsaturable losses of the annealed LT layers result...

Blueshift of bandgap energy and reduction of non-radiative defect density due to precise control of InAs-on-GaSb interface in type-II InAs/GaSb superlattice

We have investigated the influence of As-soak parameters at InAs-on-GaSb interfaces on the structural and optical parameters of InAs/GaSb superlattices (SLs). The lattice-matched SLs were obtained for two sets of technological parameters. For a long As-soak time of 12.0 s and high V/III ratio of 10, the photoluminescence (PL) analysis indicates the presence of a non-radiative recombination channel. For a shorter time of 2.8 s and a reduced V/III ratio of 5.6, the PL excitation power dependence is close to that relevant for a clear excitonic recombination. The spectral blueshift of the bandgap energy of 23 meV was observed for SLs with GaAs-like interface thicknesses of 0.4 ML and 1.0 ML and other fixed parameters.

Surface passivation of (100) GaSb using self-assembled monolayers of long-chain octadecanethiol

The passivation of (100) GaSbsurface was investigated by means of the long-chain octadecanethiol (ODT) self-assembledmonolayer(SAM). The properties of ODT SAM on (100) GaSb were characterized by the atomic force microscopy using Kelvin probe force microscopy mode and X-ray photoelectron spectroscopy. The chemical treatment of 10mM ODT-C2H5OH has been applied to the passivation of a type-II superlattice InAs/GaSb photodetector. The electrical measurements indicate that the current density was reduced by one order of magnitude as compared to an unpassivated photodetector.

Non-periodicity of peak-to-peak distances in x-ray diffraction spectrums from perfect superlattices

X-ray diffraction investigations of type II InAs/GaSb superlattice on a GaSb(001) substrate are presented. The wide range of diffraction angles (2θ/ω scans) covering 002 and 004 reflections was examined at Petra III synchrotron. The angular region between 002 and 004 reflections was the most interesting part of the measured diffraction profile. In this region, a non-coincidence of superlattice satellite peaks belonging to these two reflections is observed. The multiple-beam dynamical diffraction approach was used for correct simulation of the observed diffraction profile.

Method of determination of AlGaAsSb layer composition in molecular beam epitaxy processes with regard to unintentional As incorporation

The accurate determination of the chemical composition of multicomponent antimonide layers still remains difficult. The problem becomes even more complicated when group III antimonides are grown in a MBE chamber that is also used for the growth of group III arsenides. In this paper, the composition of MBE grown AlGaAsSb layers is investigated in the context of unintentional arsenic incorporation. Control of the As concentration and a determination of the AlGaSb composition are crucial for an accurate calculation of the AlGaAsSb stoichiometry. It has been found that when using diffraction measurements with an As detection limit of 0.087%, the Al content in Al0.5Ga0.5Sb is determined with an accuracy of ±1%. Taking into account the GaSb reference from secondary ion mass spectrometry, the accuracy can be increased to ±0.52% of Al. The Al/Ga ratio determined for AlGaSb layers is further used for the calculation of the As content in AlGaAsSb alloys grown under the same technological conditions as the ternary l...