| 1. |
- Holm, Magnus, et al.
(author)
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Calculations of the electronic structure of strained InAs quantum dots in InP
- 2002
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In: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 92:2, s. 932-936
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Journal article (peer-reviewed)abstract
- We have calculated the electronic structure of InAs quantum dots embedded in InP as a function of size, using strain dependent eight-band k.p theory in the envelope function approximation. A realistic three-dimensional shape was used for the simulations and the piezoelectric polarization of the system was included. In order to avoid spurious solutions, an extra term was added to the Hamiltonian. Polarization dependent dipole matrix elements were calculated as well as the exciton binding energies. A comparison between measurements and calculated transition energies shows good agreement. (C) 2002 American Institute of Physics.
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| 2. |
- Håkanson, Ulf, et al.
(author)
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Photon mapping of quantum dots using a scanning tunneling microscope
- 2002
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:23, s. 4443-4445
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Journal article (peer-reviewed)abstract
- Scanning tunneling microscopy (STM) and scanning tunneling luminescence (STL) have been used to investigate the geometric and optical properties of individual self-assembled InP quantum dots overgrown with a thin layer of GaInP. STL spectra and monochromatic photon maps were used to correlate the surface topography with the optical properties of single quantum dots. We find a spatial resolution of about 10 nm in the photon maps. Theoretical emission spectra were calculated by six-band k.p theory using a realistic shape of the dot as well as of the cap layer. The calculated emission spectrum of a single dot is in good agreement with the experimental findings. (C) 2002 American Institute of Physics.
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| 3. |
- Johansson, Mikael, et al.
(author)
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Correlation between overgrowth morphology and optical properties of single self-assembled InP quantum dots
- 2003
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 68:12
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Journal article (peer-reviewed)abstract
- We have studied the early stages of GaInP overgrowth on InP quantum dots (QD's) experimentally and theoretically. A direct correlation between the surface morphology and the optical properties of individual InP QD's is made using scanning tunneling microscopy (STM) and scanning tunneling luminescence. The geometric structure of the islands is further investigated using cross-sectional transmission electron microscopy (TEM). The overgrowth occurs in three stages; initially the InP QD's act as seeding points for the overgrowth, where the GaInP grows laterally from the side facets of the QD. The growth occurs preferentially in the [110] direction and elongated GaInP/InP islands are formed. As the overgrowth continues the islands increase laterally in size and GaInP also starts to grow between the islands, but not covering the top of the InP QD's. The growth of GaInP on top of the QD's commences once the islands have begun to coalesce. Using a model based on the STM and TEM results the electronic structures of the QD's have been calculated by eight-band k.p theory. The calculations are in good agreement with the experimental results. Our findings unravel the details of the strain induced energy shift of the QD luminescence previously reported [Pistol , Appl. Phys. Lett. 67, 1438 (1995)].
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| 4. |
- Lue, Tom F., et al.
(author)
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Summary of the recommendations on sexual dysfunctions in men
- 2004
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In: Journal of Sexual Medicine. - : Oxford University Press (OUP). - 1743-6109 .- 1743-6095. ; 1:1, s. 6-23
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Journal article (peer-reviewed)abstract
- Introduction. There are few published guidelines for the management of sexual dysfunctions in men and women, despite the prevalence and lack of attention to these problems. Disorders of sexual function in men include erectile dysfunction, orgasm/ejaculation disorders, priapism, and Peyronie's disease. Aim. To provide evidence-based and expert-opinion consensus guidelines for the clinical management of men's sexual dysfunctions. Methods. An International Consultation in collaboration with major urological and sexual medicine societies assembled over 200 multidisciplinary experts from 60 countries into 17 consultation committees. Committee members established the scope and objectives for each chapter. Following intensive review of available data and publications, committees developed evidence-based guidelines in each area. Main Outcome Measure. New algorithms and guidelines for assessment and treatment of men's sexual dysfunction were developed. The Oxford system of evidence-based review was systematically applied. Expert opinion was based on systematic grading of the medical literature, in addition to cultural and ethical considerations. Results. Recommendations and guidelines for men's sexual dysfunction are presented. These guidelines were developed as evidence-based, patient-centered, and multidisciplinary in focus. For the clinical assessment and diagnosis of ED, a basic evaluation was recommended for all patients, with optional and specialized testing reserved for special cases. A new treatment algorithm is proposed. This algorithm provides a clinically relevant guideline for managing ED in the large majority of men. New treatment guidelines and algorithms are provided for men's orgasm and ejaculation disorders, including premature ejaculation, retrograde and delayed ejaculation. Finally, expert opinion-based guidelines for the clinical management of priapism and Peyronie's disease are provided. Conclusions. Additional research is needed to validate and extend these guidelines. Nonetheless, this summary encompasses the recommendations concerning men's sexual dysfunctions presented at the 2nd International Consultation on Sexual Medicine in Paris, France, June 28-July 1, 2003.
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| 5. |
- Persson, Jonas, et al.
(author)
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Electron accumulation in small and larger semiconductor quantum dots
- 2002
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In: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Conference paper (peer-reviewed)abstract
- We present μ-PL and k·p calculations of self-assembled InP quantum dots (QDs) in GaInP. The QDs come in two subsets; the larger are pyramid shaped, and about 15 nm high with a base of about 40 by 50 nm, and the smaller have similar lateral extension but with a considerably lesser height. The change in size is accompanied by a change in quantum confinement and thus a change in emission energy. Moreover, there is a transition from a single sharp emission peak for the smallest dots to several 1 meV broad lines over a 50 meV range for the largest dots due to unintentional doping in the barrier material. The result is an electron accumulation in the QDs, and emission in an energy range corresponding to the energy range occupied by these electrons. Larger QDs accumulate more electrons and thus emit over a larger energy range. For the smaller dots we show that the precise position of the electronic ground state with respect to the Fermi level determines whether the dot is neutral or charged
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| 6. |
- Persson, Jonas, et al.
(author)
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Optical and theoretical investigations of small InP quantum dots in GaxIn1-xP
- 2003
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 67:3
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Journal article (peer-reviewed)abstract
- We have studied small InP quantum dots in a GaInP matrix theoretically and experimentally. Using low-temperature photoluminescence spectroscopy in conjunction with six band k.p calculations, including direct and exchange interactions, we show that the dot size is a crucial parameter that determines whether the dot is neutral or charged with electrons in the nominally undoped n-type host material. For a small enough quantum dot, the conduction-band ground state is positioned above the Fermi level and the dot remains neutral. However, as soon as the dot is large enough for the conduction-band ground state to be located below the Fermi level the dot is charged. Furthermore, we show that, for neutral quantum dots, the position of the bi-exciton emission line with respect to the exciton emission line depends on the size of the quantum dot and that the bi-exciton emission can be on either side of the exciton emission: for the smallest dots the bi-exciton emission is always at higher energy than the exciton emission but for larger dots the ordering is the opposite with the exciton emission line on the high-energy side.
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