MOCVD Growth and Characterization of Be-Doped GaN.

Beryllium has been considered a potential alternative to magnesium as a p-type dopant in GaN, but attempts to produce conductive p-GaN:Be have not been successful. Photoluminescence studies have repeatedly shown Be to have an acceptor level shallower than that of Mg, but deep Be defects and other compensating defects render most GaN:Be materials n-type or semi-insulating at best. Previous reports use molecular beam epitaxy or ion implantation to dope GaN with Be, almost exclusively.

3D GaN-based betavoltaic device design with high energy transfer efficiency.

A combined GaN 3D core-shell and planar pin structure is being developed and demonstrated to achieve the highest potential to increase energy transfer efficiency from the source (η) and power generated per cm (P/cm) in a betavoltaic (BV) device configuration. Physics-based Sentaurus TCAD and Monte Carlo N-Particle extended (MCNPX) software are employed to obtain the maximum η and P/cm by a parametric study of device dimensions coupled with a NiCl source. Idealized structure dimensions are determined to be 2 µm wide, 4 µm tall GaN pin core-shell mesas, with Ni source conformally surrounding the structure with a 2 µm gap for maximum efficiency of energy transfer.

Direct attachment of DNA to semiconducting surfaces for biosensor applications.

In this work we propose a novel method of immobilizing nucleic acids for field effect or high electron mobility transistor-based biosensors. The naturally occurring 5' terminal phosphate group on nucleic acids was used to coordinate with semiconductor and metal oxide surfaces. We demonstrate that DNA can be directly immobilized onto ZrO(2), AlGaN, GaN, and HfO(2) while retaining its ability to hybridize to target sequences with high specificity.