| AVS 63rd International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2-ThM |
| Session: | Plasma Processing of Challenging Materials |
| Presenter: | Robert Nemanich, Arizona State University |
| Authors: | R.J. Nemanich, Arizona State University F.A. Koeck, Arizona State University |
| Correspondent: | Click to Email |
Diamond has been considered as the ultimate power semiconductor because of its wide bandgap, high electron and hole mobilities, low dielectric constant and highest thermal conductivity. Recent availability of CVD diamond plates with defect densities less than 1E5 cm-2 has presented the opportunity to fabricate and characterize diamond devices. While p-type doping with boron has been known for a number of years, n-type doping during CVD growth has recently been achieved using phosphorus as the dopant. The early studies established that phosphorus can be incorporated for growth on (111) surfaces, but the incorporation is much less efficient for growth on (100) surfaces. This report describes microwave plasma CVD approaches for P-doping on both 100 and 111 surfaces while maintaining high quality epitaxy. For the (100) surfaces a pulsed growth approach is presented which results in a P-incorporation density greater than 1E18 cm-3. For growth on (111) surfaces incorporations rates approaching 1E20 cm-3 have been obtained. Using these growth approaches pin diodes have been prepared on both (111) and (100) substrates. Diodes on (100) surfaces with breakdown voltages greater than 600V have been prepared and characterized. These diodes show high forward current densities of greater than 100 A/cm2 at 5V. The diodes prepared on (111) substrates show a turn-on between 4 and 5 V indicating bipolar characteristics. An approach for fabricating pnp bipolar junction transistors is described. Simulation results indicate operation at high voltage and high power with a gain that could approach 100. The use of P-doped layers for thermionic emitters and thermionic energy conversion is also described. The P-doped diamond layers show a workfunction less than 0.8 eV which could enable a leap in thermionic energy conversion efficiency.
This research supported by ARPA-E through the SWITCHES program and by the Office of Naval Research.