Wide bandgap GaN very often shows a high electron concentration. Although several impurities such as O and Si have been identified, the concentration is not high enough to account for the number of free carriers. As a consequence native defects namely the nitrogen vacancies are widely considered to be present at high densities. Several calculations predict different energy levels of this strong...

Using the combination of high-resolution transmission electron microscopy, first-principles density-functional total energy calculations, and image simulations, we determined the atomic structure of lamellar twin and double-positioning twin boundaries in CdTe. We find that the structure of lamellar twin boundaries has no dangling bonds or wrong bonds; thus, it results in negligible effects on t...

In this paper we present an autonomous temperature sensor supplied by a on chip photovoltaic energy harvester. Then system is realized in a BCD SOI technology. The energy harvesting elements consist of a 34 trench-insulated p-n junctions, while the sensing system consists of a bandgap reference circuit, including an integrated high precision temperature sensor, and a high voltage low drop-out v...

The current paper presents an improved bandgap voltage reference (BGR) that utilizes curvature-corrected current generators which compensate for the voltage reference at lower and higher temperature range. The voltage reference is operated with a supply voltage of 2.5V to achieve an output reference of 1.1835V. The temperature coefficient achieved from the circuit is 1.342 ppm/◦C, resulting fro...

We have synthesized high quality type-II CdTe/CdSe near infrared quantum dots using successive ion layer adsorption and reaction chemistry. Transmission electron microscopy reveals that CdTe/CdSe can be synthesized layer by layer yielding quantum dots of narrow size distribution. Excitation and photoluminescence spectra reveal discrete type-II transitions, which correspond to energy lower that ...

The conventional analysis of Perdew and Levy, and Sham and Schlüter shows that the functional derivative discontinuity of the exchange-correlation density functional plays a critical role in the correct prediction of bandgaps, or the chemical hardness. In a recent work by the present authors, explicit expressions for bandgap prediction with all common types of exchange-correlation functionals h...

Semiconductors with wide bandgap are crucial for optoelectronic devices and energy applications owing to their electron confinement, high optical transparency tunable electrical conductivity. Therefore, in this study, the quantum confinement effect of chalcogenide semiconductor nanocrystals such as ZnS, ZnSe, ZnTe, SnS, SnSe SnTe studied based on Brus model using effective mass approximation, h...