Polycrystalline Diamond Junction Field Effect Transistors (JFETS)1

摘要

Diodes were fabricated from in situ doped 'N'-diamond/P-diamond layer structures.The 'N'-dopants investigated were nitrogen and oxygen. The majority of the diodes fabricated to date have has either'leaky' characteristics or displayed high series resistance. As these diodes are designed to be gate electrodes, series resistance may be acceptable. SIMS measurements were performed on polycrystalline diamond films of diode structures to evaluate the doping efficiency of boron, nitrogen and oxygen. Boron doping efficiency was found to be very high with measured doping concentrations (polydiamond) of 5 x 10 to the 21st power boron per cu cm (based on a boron doped single crystal diamond calibration). The dopant concentrations, as measured by SIMS, of both nitrogen and oxygen was found to be too low, in the films analyzed, to create the desired N+(deep donor)/P+(boron) diamond diodes. The diode doping levels are limited by the currently achievable donor dopant concentrations to approximately 1.0 x 10 to the 19th power per cu cm. Electron channelling measurements were performed on boron doped diamond grown on type IIA natural diamond. These measurements confirmed the epitaxial relationship between CVD diamond layers grown in the plasma apparatus used for this study. (RRH)