We present a model for the description of dark IV curves in midinfrared quantum well infrared photodetectors at low temperatures, in a regime where dark current is dominated by interwell tunneling. The model separates the IV curve into a low-field and a high-field region allowing us to identify the effects ascribed to miniband transport and carrier localization, respectively. At low fields the ...

i Acknowledgments ii List of original papers v

The Quantum Cascade ~QC! laser is a unipolar semiconductor laser that has demonstrated high performance in pulsed operation in the mid-infrared wavelength range ~4–12 mm!. There has been a large effort to develop such devices for even longer wavelengths. These sources would be especially valuable for the detection of large organic hydrocarbon molecules like the BTX compounds in the 12–16 mm reg...

A two-dimensional electron gas in a static external magnetic field exhibits two distinct collective excitation modes. The lower frequency mode propagates along the periphery of domain almost freely with an extended lifetime, which is referred to as edge magnetoplasmons. Peculiar phenomena caused by capacitive interaction between nearest-neighbor domains are known, such emergence Tomonaga-Luttin...

what is engineering and who is an engineer that changed our world so drastically? based on what type of education the engineers have gained the power to do this? what should we do for becoming successful in our professional career? engineers receive competencies in one of the engineering branches during their school years but less effort is made to answer the above questions. in other word, uni...

In this paper, we study the effect of single Boron/Nitrogen impurityatom on electronic properties of a silicene nano flake. Our calculations are basedon density functional theory by using Gaussian package. Here, one Si atom insilicene nano flake substitutes with a Boron/Nitrogen atom. The results show thatsubstitution of one Si atom with single Boron/Nitrogen atom increases distanceof impurity ...

We fabricated a three-dimensional (3D) stacked Si nanodisk (Si-ND) array with a high aspect ratio and uniform size by using our advanced top-down technology consisting of bio-template and neutral beam etching processes. We found from conductive atomic microscope measurements that conductivity became higher as the arrangement was changed from a single Si-ND to two-dimensional (2D) and 3D arrays ...

It has been shown that coherent phonons can be used as a potent tool for controlling and enhancing optoelectronic transport properties of nanostructured materials. Recent studies revealed interaction acoustic fast-moving carriers in semiconductor heterostructures accompanied by electron-phonon instabilities cause ordinary induced Cherenkov effects. However, the development such is still poorly ...

Semiconductor superlattices are interesting for two distinct reasons: the possibility to design their structure (band-width(s), doping, etc.) gives access to a large parameter space where different physical phenomena can be explored. Secondly, many important device applications have been proposed, and then subsequently successfully fabricated. A number of theoretical approaches has been used to...