Eight-band k⋅p calculations of the composition contrast effect on the linear polarization properties of columnar quantum dots

We present eight-band k . p calculations of the electronic and polarization properties of columnar InzGa1-zAs quantum dots (CQD) with high aspect ratio embedded in an InxGa1-xAs/GaAs quantum well. Our model accounts for the linear strain effects, linear piezoelectricity, and spin-orbit interaction. We calculate the relative intensities of transverse-magnetic (TM) and transverse-electric (TE) linear polarized light emitted from the edge of the semiconductor wafer as a function of the two main factors affecting the heavy hole-light hole valence band mixing and hence, the polarization dependent selection rules for the optical transitions, namely, (i) the composition contrast z/x between the dot material and the surrounding well and (ii) the dot aspect ratio. The numerical results show that the former is the main driving parameter for tuning the polarization properties. This is explained by analyzing the biaxial strain in the CQD, based on which it is possible to predict the TM to TE intensity ratio. The conclusions are supported by analytical considerations of the strain in the dots. Finally, we present the compositional and geometrical conditions to achieve polarization independent emission from InGaAs/GaAs CQDs. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3346552

Submonolayer uniformity of type II InAs/GaInSb W-shaped quantum wells probed by full-wafer photoluminescence mapping in the mid-infrared spectral range

The work has been supported by Project Widelase (No. 318798) of the 7-th Framework Program of the European Commission. Date of Acceptance: 06/10/2015The spatial uniformity of GaSb- and InAs substrate-based structures containing type II quantum wells was probed by means of large-scale photoluminescence (PL) mapping realized utilizing a Fourier transform infrared spectrometer. The active region was designed and grown in a form of a W-shaped structure with InAs and GaInSb layers for confinement of electrons and holes, respectively. The PL spectra were recorded over the entire 2-in. wafers, and the parameters extracted from each spectrum, such as PL peak energy position, its linewidth and integrated intensity, were collected in a form of two-dimensional spatial maps. Throughout the analysis of these maps, the wafers' homogeneity and precision of the growth procedure were investigated. A very small variation of PL peak energy over the wafer indicates InAs quantum well width fluctuation of only a fraction of a monolayer and hence extraordinary thickness accuracy, a conclusion further supported by high uniformity of both the emission intensity and PL linewidth.Publisher PDFPeer reviewe

Fourier Transformed Photoreflectance and Photoluminescence of Mid Infrared GaSb-Based Type II Quantum Wells

Fourier-transformed photoreflectance and photoluminescence have been used to study the optical transitions in type 11 quantum wells (QWs) ranging up to almost 5 mu m. High signal-to-noise ratio spectral features resulting from fundamental and excited state transitions have been detected for molecular beam epitaxially grown GaSb/AlSb/InAs/InGaSb/InAs/AlSb/GaSb "W"-shaped QW structures designed for laser-based gas sensing applications in the mid-infrared. The spectral features' dependence on arsenic pressure during growth process and on InAs confining-layer thickness could be followed unambiguously at room temperature. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.126505</p

Immersion Layer in Columnar Quantum Dash Structure as a Polarization Insensitive Light Emitter at 1.55 mu m

We report on polarization independent 1.55 mu m room temperature edge emission from an InGaAs immersion layer, being a quasi-two-dimensional surrounding of columnar quantum dashes formed during the close stacking self assembled growth. Calculations performed in an 8 band k-p model revealed that the in-plane strain distribution across the immersion layer induces a significant heavy hole-light hole valence states mixing leading to equal transverse electric and transverse magnetic components of the optical transition intensity. (C) 2009 The Japan Society of Applied Physics</p

Towards polarization insensitive semiconductor optical amplifiers using InAs/GaAs columnar quantum dots

We report columnax quantum dots (CQDs) with extremely large aspect ratios, showing nearly polarization-insensitive electroluminescence. A systematic experimental and theoretical investigation of their polarization properties as a function of aspect ratio is also reported. (c) 2008 Optical Society of Americ

Polarization Properties of Columnar Quantum Dots: Effects of Aspect Ratio and Compositional Contrast

We report a systematic theoretical and experimental investigation of the polarization properties of columnar quantum dots (CQDs) with extremely large aspect ratio and high compositional contrast. A strong variation of the polarization of the dominant interband transitions as a function of the CQD composition and aspect ratio is predicted by the theory and observed experimentally. In optimized InAs CQDs grown on GaAs, dominant emission and lasing is obtained in the transverse-magnetic polarization, which shows the potential of this approach for polarization-independent amplifiers on GaAs