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Small-signal analysis and polarization stability performance of single-mode VCSELs for MEMS atomic clock applications " , in Proc. [3] A. Gadallah and R. Michalzik, " Densely-packed 2-D matrix-addressable vertical-cavity surface-emitting laser arrays " , in Proc. High-power single-higher-order-mode VCSELs for optical particle manipulation " , in(More)
Selective-area epitaxy is used to form three-dimensional (3D) GaN structures providing semipolar crystal facets. On full 2-in. sapphire wafers we demonstrate the realization of excellent semipolar material quality by introducing inverse GaN pyramids. When depositing InGaN quantum wells on such a surface, the specific geometry influences thickness and(More)
We study the lasing dynamics of individual ZnO nanorods by time-resolved mu-photoluminescence. The distinct laser modes show gain competition and pronounced shifts as a function of excitation density. This behavior can be understood in terms of many-particle effects within an inverted electron-hole plasma and of the calculated mode spectra of the particular(More)
This article reviews the piezoelectric properties of III-nitrides with emphasis on GaN, InN, and their ternary alloys. After a short literature survey we concentrate on semipolar and nonpolar quantum wells grown on crystal planes other than the commonly used c plane ({0001}). The electrostatic field within a quantum well causes a quantum confined Stark(More)
We report on the development of a diamond-on-sapphire microelectrode quadrupole array, substituting the commonly used inert metal electrode material by nano-crystalline diamond (NCD). This allows to combine the transparency (desired for fluorescence analysis) with the properties of an inert quasi-metallically doped diamond electrode. The NCD film was(More)
Ga x In 1−x N quantum wells grown by metal organic vapor phase epitaxy on a plane GaN grown on r plane sapphire substrate typically show relatively large surface pits. We show by correlation of low temperature photoluminescence, cathodoluminescence, scanning and transmission electron microscopy that the different semipolar side facets of these pits dominate(More)
ZnO-based hollow nanoparticles by selective etching: elimination and reconstruction of metal-semiconductor interface, improvement of blue emission and photocatalysis, Polymeric anodes from poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) for 3.5% efficient organic solar cells, In situ monitoring the drying kinetics of knife coated polymer-fullerene(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)