A 0.2-W Heterostructure Barrier Varactor Frequency Tripler at 113 GHz

We present a high-power InAlAs/InGaAs/InP heterostructure barrier varactor (HBV) frequency tripler. The HBV device topology was designed for efficient thermal dissipation and high efficiency. To verify simulations, the device was flip-chip soldered onto embedding microstrip circuitry on an aluminum nitride substrate. This hybrid circuit was then mounted in a waveguide block without any movable tuners. From the resulting RF measurements, the maximum output power was 195 mW at 113 GHz, with a conversion efficiency of 15%. The measured 3-dB bandwidth was 1.5%     

11% efficiency 100 GHz InP-based heterostructure barrier varactor quintupler

A record conversion efficiency of 11.4% at 100 GHz using a heterostructure barrier varactor (HBV) quintupler is demonstrated. The quintupler is based on a microstrip circuit mounted in a full-height crossed-waveguide block. The nonlinear element consists of a planar HBV diode fabricated in InGaAs/InAlAs/AlAs epitaxial layers on an InP substrate     

An Approach for Sub-Second Imaging of Concealed Objects Using Terahertz (THz) Radar

High-resolution, long-range detection of person-borne concealed weapons has recently been demonstrated using a terahertz imaging radar. However, the radar’s image acquisition time must be greatly shortened, from minutes to less than one second, before the system can be effectively deployed in a real-life threat environment. Here we analyze the major system modifications necessary for increasing the speed of a terahertz imaging radar by up to two orders of magnitude.     

Vertical high-mobility wrap-gated InAs nanowire transistor

In this letter, the authors demonstrate a vertical wrap-gated field-effect transistor based on InAs nanowires [Proc. DRC, 2005, p. 157]. The nanowires have a diameter of 80 nm and are grown using selective epitaxy; a matrix of typically 10 /spl times/ 10 vertically standing wires is used as channel in the transistor. The authors measure current saturation at V/sub ds/=0.15 V (V/sub g/=0 V), and a high mobility, compared to the previous nanowire transistors, is deduced.     

Electron beam pre-patterning for site-control of self-assembled InAs quantum dots on Inp surfaces

A site control technique for individual InAs quantum dots (QDs) formed by self-assembling has been developed, using scanning electron microscope (SEM) assisted nano-deposition and metal organic vapor phase epitaxy (MOVPE). In a first step we characterize a device with randomly distributed InAs QDs on InP, using resonant tunneling and transmission electron microscopy (TEM). Secondly, we use nano-scale deposits, created at the focal point of the electron beam on an InP based heterostructure, as “nano growth masks”. Growth of a thin InP layer produces nano-holes above the deposits. The deposits are removed by oxygen plasma etching. When InAs is supplied on this surface, QDs are self-assembled at the hole sites, while no InAs dots are observed in the flat surface region. A vertical single electron tunneling device is proposed, using the developed technique.