Femtosecond ultrabright cathodes with spatially structured emission are a critical technology for applications such as free-electron lasers, tabletop coherent x-ray sources, and ultrafast imaging. In this work, the optimization of the total electron yield of ultrafast photon-triggered field emission cathodes composed of arrays of nanosharp, high-aspect-ratio, single-crystal silicon pillars is e...

SiGe heterojunction bipolar transistors (HBTs) have been fabricated using selective epitaxy for the Si collector, followed in the same growth step by nonselective epitaxy for the p SiGe base and n-Si emitter cap. DC electrical characteristics are compared with cross-section TEM images to identify the mechanisms and origins of leakage currents associated with the epitaxy in two different types o...

We demonstrate multi-emitter Si/GexSi1 x npn heterojunction bipolar transistors (HBT’s) which require no base contact for transistor operation. The base current is supplied by the additional emitter contact under reverse bias due to the heavy doping of the emitter-base junction. Large-area HBT test structures exhibit good transistor characteristics, with current gain 400 regardless of whether t...

A molecular beam epitaxy grown wavelength tunable GaAs p-i homojunction interfacial work-function internal photoemission far-infrared detector is developed. The multilayer (p-ip-i. . . ! detector structures consist of 2, 5, and 10 emitter layers. Experimental results are explained in terms of the number of emitter layers and the doping concentrations of the emitter layer. A detector with 10 mul...

The use of beam interference in combination with a large-area photoconductive emitter for the generation of pulsed terahertz (THz) radiation is presented. An interference pattern with a period twice that of the THz emitter is generated with a transmission phase grating, placed directly in front of the photoconductive emitter. This way, efficient THz generation is achieved with a single metallis...

A laboratory soil column experiment was first conducted to analyze water movement in latosol of sugarcane field under drip irrigation from single-point source at different emitter discharge rates. Next, a mathematical model of soil water movement under drip irrigation from single-point source was built using Hydrus-3D, which could accurately simulate the shape of the wetted soil volume and the ...

Self-aligned selective-emitter cells have been fabricated using a self-doping paste by co-firing the front and back contacts. Good ohmic contacts with ~0.774 fill factor were obtained on 100 Ω/sq. emitters after alloying the self-doping Ag grid by a 900°C spike firing in a belt furnace. Screen-printed selective emitter Fz Si cells gave an efficiency of 16.4%. Selective-emitter cells with effect...

introduction: an appropriate water resources management and planning is necessary due to the scarcity of water resources and rapidly growing world population. in this regard, selecting appropriate methods for irrigation is one of the most important issues. drip irrigation is a recent advanced irrigation method in which fertilizers can be efficiently applied along with irrigation water. drip fer...