Dagmar Gerthsen

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In this study, we investigated pre-structured (100) GaAs sample surfaces with respect to subsequent site-selective quantum dot growth. Defects occurring in the GaAs buffer layer grown after pre-structuring are attributed to insufficient cleaning of the samples prior to regrowth. Successive cleaning steps were analyzed and optimized. A UV-ozone cleaning is(More)
The effect of growth temperature on AlAs/GaAs resonant tunneling diodes Formation of unstrained Si 1-x Ge x layers by high-dose 74 Ge ion implantation in SIMOX High-resolution electron microscopy and X-ray diffraction characterization of alternately strained (GaAs) n (GaP) m (GaAs) n (InP) m superlattices grown by atomic layer epitaxy Structural properties(More)
We observe ultraviolet photoluminescence from sputtered ZnO quantum dots which are fabricated with no annealing steps. The nanocrystals are embedded in amorphous SiO2 and exhibit a narrow size distribution of 3.5 ± 0.6 nm. Photoluminescence and transmittance measurements show a shift of ultraviolet emission and absorption of the dots compared to bulk ZnO(More)
Structure analysis of the cell-penetrating peptide transportan 10 (TP10) revealed an exemplary range of different conformations in the membrane-bound state. The bipartite peptide (derived N-terminally from galanin and C-terminally from mastoparan) was found to exhibit prominent characteristics of (i) amphiphilic α-helices, (ii) intrinsically disordered(More)
We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs(More)
Group III nitrides are promising materials for light emitting diodes (LEDs). The occurrence of structural defects strongly affects the efficiency of these LEDs. We investigate the optical properties of basal plane stacking faults (BFSs), and the assignment of specific spectral features to distinct defect types by direct correlation of localized emission(More)
Zinc oxide (ZnO) nanocrystals (NCs) with high crystalline quality were prepared via radio-frequency magnetron sputtering as a SiO(2)/ZnO/SiO(2) trilayer on Si(100) and Al(2)O(3)(0001) substrates with an intermediate in situ annealing step. Transmission electron microscopy reveals a uniform dispersion of ZnO NCs in the amorphous SiO(2) matrix with typical(More)
Analysis of composition fluctuations in InGaN by transmission electron microscopy phys. stat. sol. Coexistence of planar and three-dimensional quantum dots in CdSe/ZnSe structures Structural and chemical investigation of In 0.6 Ga 0.4 As Stranski-Krastanow layers buried in GaAs by transmission electron microscopy Character of the Cd-distribution in(More)
Determination of the mean inner potential in III-V semiconductors, Si and Ge by density functional theory and electron holography Strain state analysis of InGaN/GaN –sources of error and optimised imaging conditions Phys. Electron holography of thin amorphous carbon films: measurement of the mean inner potential and a thickness-independent phase shift(More)