William Andrew Hennessy

Nitrogen-implanted SiC diodes using high-temperature implantation

6H-SiC diodes fabricated using high-temperature nitrogen implantation up to 1000 degrees C are reported. Diodes were formed by RIE etching a 0.8- mu m-deep mesa across the N/sup +//P junction using NF/sub 3//O/sub 2/ with an aluminum transfer mask. The junction was passivated with a deposited SiO/sub 2/ layer 0.6 mu m thick. Contacts were made to N/sup +/ and P regions with thin nickel and aluminum layers, respectively, followed by a short anneal between 900 and 1000 degrees C. These diodes have reverse-bias leakage at 25 degrees C as low as 5*10/sup -11/ A/cm/sup 2/ at 10 V.<<ETX>>

Silicon carbide MOSFET technology

Abstract The research and development activities carried out to demonstrate the status of MOS planar technology for the manufacture of high temperature SiC ICs will be described. These activities resulted in the design, fabrication and demonstration of the worlds first SiC analog IC—a monolithic MOSFET operational amplifier. Research tasks required for the development of a planar SiC MOSFET IC technology included: characterization of the SiCSiO2 interface using thermally grown oxides; high temperature (350°C) reliability studies of thermally grown oxides; ion implantation studies of donor (N) and acceptor (B) dopants to form junction diodes; epitaxial layer characterization; device isolation methods; and finally integrated circuit design, fabrication and testing of the worlds first monolithic SiC operational amplifier IC. High temperature circuit drift instabilities at 350°C were characterized. These studies defined an SiC depletion model MOSFET IC technology and outlined tasks required to improve all types of SiC devices.

Gated Diode Design to Mitigate Radiation Damage in X-Ray Imagers

Radiation damage of amorphous silicon X-ray imagers leads to degradation of the detectors performance due to increased diode perimeter leakage. To reduce the effect of this damage, a novel pixel device based on a gated diode was fabricated. The additional gate metalization placed on the perimeter of the diode modulates the surface side-wall leakage and has been tested up to a 64 kGy absorbed dose in the diode. This new pixel design significantly reduces the increase in diode leakage and noise due to radiation damage, providing a more uniform performance and extending the lifetime of the imager.