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Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors. cop. 2015 AIP Publishing LLC.

We present the performance of a novel InGaAs/InP single-photon avalanche diode (SPAD) with high detection efficiency and low noise thanks to the improvement of Zinc diffusion conditions and the optimization of the vertical structure. The 25-μm active-area diameter detector, operated in gated-mode with ON time of tens of nanoseconds, shows very low dark count rate (few kilo-counts per second at 225 K and 5 V of excess bias), 30% photon detection efficiency at 1550 nm, low afterpulsing, and a timing response with less than 90-ps full-width at half maximum and very fast exponential tail (time constant ~ 60 ps). Therefore, this InGaAs/InP SPAD is among the best ones ever reported in the literature.

We report in detail on the luminescence imaging setup developed within the last years in our laboratory. In this setup, the luminescence emission of silicon solar cells or silicon wafers is analyzed quantitatively. Charge carriers are excited electrically (electroluminescence) using a power supply for carrier injection or optically (photoluminescence) using a laser as illumination source. The luminescence emission arising from the radiative recombination of the stimulated charge carriers is measured spatially resolved using a camera. We give details of the various components including cameras, optical filters for electro- and photo-luminescence, the semiconductor laser and the four-quadrant power supply. We compare a silicon charged-coupled device (CCD) camera with a back-illuminated silicon CCD camera comprising an electron multiplier gain and a complementary metal oxide semiconductor indium gallium arsenide camera. For the detection of the luminescence emission of silicon we analyze the dominant noise sources along with the signal-to-noise ratio of all three cameras at different operation conditions. © 2011 American Institute of Physics.

We report on single dot microphotoluminescence (μPL) emission at low temperature and low power from InAs dots grown by molecular beam epitaxy in nanoscale holes of a SiO2 mask deposited on GaAs(001). By comparing atomic force microscopy measurements with μPL data, we show that the dot sizes inside the nanoholes are smaller than those of the dots nucleated on the extended GaAs surface. PL of dots spans a wide energy range depending on their size and on the thickness and composition of the InGaAs capping layer. Time-resolved PL experiments demonstrate a negligible loss of radiative recombination efficiency, proving highly effective in the site-controlled dot nucleation.

A controlled method of manipulation of nanowires was found using the tip of an Atomic Force Microscope (AFM). Manipulation is done in the ‘Retrace Lift’ mode, where feedback is turned off for the reverse scan and the tip follows a nominal path. The effective manipulation force during the reverse scan can be changed by varying an offset in the height of the tip over the surface. Using this method, we have studied InAs nanowires on different substrates. We have also investigated interactions between wires and with gold features patterned onto the substrates.

Date of Conference: 6-11 May 2007 The electro-optic coefficients of self-organized InAs quantum dot layers in molecular beam epitaxy grown laser structures in reverse bias have been investigated. Enhanced electrooptic coefficients compared to bulk GaAs were observed. © 2003 Optical Society of America.