Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs ...

The experimental observation of Bloch oscillations in solids was long thought to be out of experimental reach. The invention of the semiconductor superlattice has changed this situation decisively. Transport experiments performed in the past two decades have given indirect evidence for the existence of Bloch oscillations. Recently, it has been possible to directly observe Bloch oscillations in ...

Shot noise affects differently the nonlinear electron transport in semiconductor superlattices depending on the strength of the coupling among the superlattice quantum wells. Strongly coupled superlattices can be described by a miniband Boltzmann-Langevin equation from which a stochastic drift-diffusion equation is derived by means of a consistent Chapman-Enskog method. Similarly, shot noise in...

Quasi one-dimensional nanowires possess unique electrical, electronic, thermoelectrical, optical, magnetic and chemical properties, which are different from that of their parent counterpart. The physical properties of nanowires are influenced by the morphology of the nanowires, diameter dependent band gap, carrier density of states etc. Nanowires hold lot of promises for different applications....

We report here a preparation and an examination of the electronic properties of a semiconductor (tungsten oxide) monolayer on silica particles (0.18 pm). This material is similar to the Q-state particles reported by Henglein and co-workers [ 11, Brus and co-workers [ 21, Nozik et al. [ 31, Watzke and Fendler [ 41 and others. Our particles differ from Q-state particles that are small ( =20-100 A...

The dynamic, nonlocal and spatially inhomogeneous polarizability and dielectric function are discussed in this paper for a Coulomb-coupled system of a periodic lateral superlattice array of one-dimensional quantum wire plasmas in the vicinity of a semi-infinite bulk plasma. The spacetime matrix inverse of the dielectric function, i.e: the dynamic, nonlocal, inhomogeneous screening function of t...

Manufactured, reproducibly layered structures having layer thicknesses approaching interatomic distances. Modern thin-film techniques are at a stage at which it is possible to fabricate these structures, also known as artificial crystals or superlattices, opening up the possibility of engineering new desirable properties into materials. In addition, a variety of problems in solid-state physics ...

Infrared photodetectors (IRPDs) have become important devices in various applications such as night vision, military missile tracking, medical imaging, industry defect imaging, environmental sensing, and exoplanet exploration. Mature semiconductor technologies such as mercury cadmium telluride and III–V material-based photodetectors have been dominating the industry. However, in the last few de...

The structure and morphology of mixed thin films of picene (C22H14, PIC) and perfluoropentacene (C22F14, PFP) as well as mixed thin films of PIC and pentacene (C22H14, PEN) grown by simultaneous coevaporation is investigated using X-ray diffraction, atomic force microscopy, and near-edge X-ray absorption spectroscopy. For both systems we find mixing on the molecular level and the formation of m...