We present the design, fabrication and characterisation of an intersubband detector employing a resonant metamaterial coupling structure. The semiconductor heterostructure relies on a conventional THz quantum-cascade laser design and is operated at zero bias for the detector operation. The same active region can be used to generate or detect light depending on the bias conditions and the vertic...

We present a polarization-independent metamaterial design for the construction of electrically tunable terahertz (THz) devices. The implemented structure consists of an array of gold crosses fabricated on top of an n-doped gallium arsenide (GaAs) layer. Utilizing THz time-domain spectroscopy, we show that the electric resonance and thus the transmission properties of the cross structure can be ...

We have implemented parallel algorithms for density-functional-theory (DFT) based electronic-structure calculations. These include a plane-wave based algorithm, a real-space-grid algorithm based on a high-order finite difference method, and a linear-scaling real-space algorithm using localized orbitals. Parallelization schemes are described for these algorithms, and the computational complexity...

We measure the lasing dynamics of single and coupled photonic crystal nanocavity array lasers fabricated in the indium gallium arsenide phosphide material system. Under short optical excitation, single cavity lasers produce pulses as fast as 11 ps full width at half maximum , while coupled cavity lasers show significantly longer lasing duration which is not explained by a simple rate equation m...

We introduce two CAD tools, checkT, and minT, , for timing verification and optimal clocking. Both tools are based on a new timing model of synchronous digital circuits which is: 1) general enough to handle arbitrary multiphase clocking; 2) complete, in the sense that it captures signal propagation along short as well as long paths in the logic; 3) extensible to make it relatively easy to incor...

Efficient near-infrared detection of specific DNA with single nucleotide polymorphism selectivity is important for diagnostics and biomedical research. Herein, we report the use of gallium arsenide (GaAs) as a sensing platform for probing DNA immobilization and targeting DNA hybridization, resulting in ∼8-fold enhanced GaAs photoluminescence (PL) at ∼875 nm. The new signal amplification strateg...

A GaAs 63Ni radioisotope betavoltaic cell is reported over the temperature range 70°C to -20°C. The temperature effects on the key cell parameters were investigated. The saturation current decreased with decreased temperature; whilst the open circuit voltage, the short circuit current, the maximum power and the internal conversion efficiency values decreased with increased temperature. A maximu...

The temperature stability of Ge/Au/Ni/Au ohmic contacts to GaAs nanoheterostructures and Ti/Al/Ni/Au GaN on silicon substrate was investigated. It has been established that optimization the RTA process made it possible obtain with field emission current flow mechanism. thermal for transistors mesa resistors demonstrated threshold behavior heat treatment temperature. optimum parameters minimum c...