A novel method of introducing a notch at a point of high magnetic field in a coplanar waveguide (cpw) radial and diamond stub resonator to increase the quality factor (Q) was analysed. For comparison both radial and diamond shaped cpw resonators with and without notches were fabricated on gallium arsenide (GaAs) semi-insulating substrate at the James Watt Nanofabrication Centre and tested in th...

We report on the use of graphene for room temperature on-chip detection and generation of pulsed terahertz (THz) frequency radiation, exploiting the fast carrier dynamics of light-generated hot carriers, and compare our results with conventional low-temperature-grown gallium arsenide (LT-GaAs) photoconductive (PC) switches. Coupling of picosecond-duration pulses from a biased graphene PC switch...

We report a large spin-polarized current injection from a ferromagnetic metal into a nonferromagnetic semiconductor, at a temperature of 100 Kelvin. The modification of the spin-injection process by a nanoscale step edge was observed. On flat gallium arsenide [GaAs(110)] terraces, the injection efficiency was 92%, whereas in a 10-nanometer-wide region around a [111]-oriented step the injection ...

We present a computational and experimental study of a novel terahertz (THz) device resulting from hybridization of metamaterials with pseudomorphic high electron mobility transistors (HEMTs), fabricated in a commercial gallium arsenide (GaAs) process. Monolithic integration of transistors into each unit cell permits modulation at the metamaterial resonant frequency of 0.46 THz. Characterizatio...

Until recently, WiMAX systems have used technology processes such as Gallium-Arsenide (GaAs) to obtain the performance needed from the RF circuits. Although these technologies provide the functional performance required by radios today, they do not support the cost/scalability business model. This paper outline the design of a power amplifier (PA) for WiMAX base station applications at 3.5GHz b...

1. Abstract There is a great demand for the ultrafast testing of high-speed electronic/optoelectroi~ic devices in various fields of science and engineering. Such testing can be achieved by electro-optic (EO) sanlpling systems that are capable of sampling picosecond voltage signals with subpicoseco~ld time resolution. Samples of gallium arsenide (GaAs), a semiconductor, with metal-semiconductor-...

In a new approach, we have fabricated 6:1 aspect ratio magnetic nanocolumns, 60–250 nm in diameter, embedded in a hard aluminum-oxide/gallium-arsenide (Al2O3 /GaAs) substrate. The fabrication technique uses the highly selective etching properties of GaAs and AlAs, and highly efficient masking properties of Al2O3 to create small diameter, high aspect ratio holes. Nickel ~Ni! is subsequently elec...

We report the detection of the inverse spin Hall effect (ISHE) in n-gallium arsenide (n-GaAs) combined with electrical injection and modulation of the spin current. We use epitaxial ultrathin-Fe/GaAs injection contacts with strong in-plane magnetic anisotropy. This allows us to simultaneously perform Hanle spin-precession measurements on an Fe detection electrode and ISHE measurements in an app...

In this paper, the output electric pulse characteristics of gallium arsenide photoconductive semiconductor switch (GaAs PCSS) with bias voltage 20 kV and width about 100 ns are studied. By designing reflection transmission optical paths, absorption rate trigger GaAs PCSS at a wavelength 1064 nm was measured to be 24.8%. When is 16 kV-20 kV, avalanche multiplication rates carriers calculated res...

Widely tunable, Fourier-transform-limited pulses of terahertz (THz) radiation have been generated using (i) crystals of the highly nonlinear organic salt 4-N ,N -dimethylamino-4-N -methyl stilbazolium tosylate (DAST), (ii) zinc telluride (ZnTe) crystals, (iii) gallium phosphide (GaP) crystals, and (iv) low-temperature-grown gallium arsenide (LTG-GaAs) photomixers with THz spiral antennas. Outpu...