No abstract

We demonstrate the use of a magnetic field to switch and to control the direction and polarization of a THz beam radiated from a semiconductor emitter.

A Monte Carlo particle (MCP) bipolar model for 4H-SiC consisting of three electron and two hole bands is developed to simulate the millimetre wave power generation by 4H-SiC IMPATT diodes. Validation of the model is provided by comparing (i) carrier transport properties with full band simulation results and (ii) hole impact ionization coefficients with the most recent experimental results. MCP simulation results are reported for a low-voltage 4H-SiC IMPATT diode connected directly in a parallel resonant circuit with a standard 50 load resistor. The detailed evolution of carrier generation, accumulation and drift are presented to confirm the design of an efficient hi-lo IMPATT diode structure. Critical performance parameters investigated include bias and frequency dependences of millimetre wave output power, generation efficiency, conduction current and frequency stability at an operating frequency around 200 GHz. It is predicted that very high-power millimetre waves at around 200 GHz can be generated at pulse mode.

Expressions for the direct and alternating output voltages of Cockcroft-Walton voltage multipliers with an arbitrary number of stages are determined for the joint effects of charge dissipation in the load resistance and charge storage in the diode shunt capacitances.

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ) for hole (electron) injection, was measured with 365-nm light in both structures. Modeling the experimental results using a simple quantum efficiency model and a nonlocal description yields effective ionization threshold energies of 12 and 8 eV for electrons and holes, respectively, and suggests that the dead space in 4H-SiC is soft. Although dead space is important, pure hole injection is still required to ensure low excess noise in thin 4H-SiC APDs owing to ratios that remain large, even at very high fields.