Organometal halide perovskite semiconductors have emerged as promising candidates for optoelectronic applications because of the outstanding charge carrier transport properties, achieved with low-temperature synthesis. Here, we present highly sensitive sub-bandgap external quantum efficiency (EQE) measurements of Au/spiro-OMeTAD/CH3NH3Pb(I1−xBrx)3/TiO2/FTO/glass photovoltaic devices. The room-t...

Sb-based pN heterojunction diodes at 6.2 Å, consisting of narrow bandgap p-type In0.27Ga0.73Sb and wide bandgap n-type In0.69Al0.41As0.41Sb0.59, have been fabricated and measured. These diodes show excellent electrical characteristics with an ideality factor of 1.2 and high current density. S-parameter measurements and subsequent analysis show that these diodes have RC-cutoff frequencies over 1...

A new theoretical model to calculate the effective surface recombination velocity ($a) of a high-low junction with an arbitrary impurity distribution is presented. The model is applied to erfc-diffused pp+ junctions using experimental data of bandgap narrowing, lifetime and mobility. Bandgap narrowing is shown to degrade the minority carrier reflecting properties of the high-low junction. Compu...

We describe the design and characterization of solid core large mode area bandgap fibers exhibiting low propagation loss and low bend loss. The fibers have been prepared by modified chemical vapor deposition process. The bandgap guidance obtained thanks to a 3-bilayer periodic cladding is assisted by a very slight index step (5.10-4) in the solid core. The propagation loss reaches a few dB/km a...

This brief presents experimental and modeling results of device noise in SiGe HBT RF technology. By careful bandgap engineering, a simultaneous reduction of RF noise, 1 noise, and phase noise has been achieved. At a given , transistors with different base bandgap profiles show similar 1 noise. At a given , however, transistors with a higher (and hence lower RF noise) show lower 1 noise. Circuit...

This paper presents an example of the CMOS bandgap voltage reference design. Proposed circuit is evaluated with a set of simulations. Simulation results show the circuit performance. Circuit exhibits the nominal temperature coefficient of 6 ppm/°C, and dc power supply rejection of 130 dB.

Hexagonal boron nitride is a wide bandgap semiconductor with very high thermal and chemical stability that is used in devices operating under extreme conditions. The growth of high-purity crystals has recently revealed the potential of this material for deep ultraviolet emission, with intense emission around 215 nm. In the last few years, hexagonal boron nitride has been attracting even more at...

In this article, we investigate composite media which present both a local resonance and a periodic structure. We numerically and experimentally consider the case of a very academic and simplified system that is a quasi-one dimensional split ring resonator medium. We modify its periodicity to shift the position of the Bragg bandgap relative to the local resonance one. We observe that for a well...

Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of a suitable low-bandgap polymer. Here, we demonstrate highly efficient single and tandem polymer solar c...