Diamond is a wide bandgap material with superior electric properties that has been studied in recent years for use in high power and high frequency electronics applications. Doping of the diamond material is necessary for effective control of defect formation, and is typically achieved by incorporating the dopant (e.g., phosphorous, boron) into the diamond lattice during its growth.
This doping process takes place at elevated temperatures using microwave plasma enhanced chemical vapor deposition (MPECVD) and hot filament chemical vapor deposition (HFCVD) to form species from introduced gases, typically hydrogen and methane with oxygen as an additional option. However, the predominant doping sources typically used in this process (e.g., phosphine, diborane) are highly toxic and can be expensive for larger-scale applications.
Researchers at Arizona State University have developed a novel method for doped diamond growth using a solid-state diffusion source. The solid-state source is a lower toxicity compound that can be more economically deployed, and is readily available due to existing widespread use in silicon technology. Commercially available diffusion sources for boron and phosphorous can be utilized in this method. The dopant evolves in the growth plasma when heated, and becomes incorporated in the diamond crystal. Doping controls can be put in place by varying the solid-state diffusion source temperature and the plasma power.
Potential Applications:
- High frequency electronics
- Power switch applications
Benefits and Advantages:
- Lower toxicity – removes need for highly toxic doping sources
- Lower cost – uses commercially available sources of boron and phosphorous and does not require use of expensive gas dopants
- Greater control – doping parameters can be changed by varying diffusion source temperatures and plasma power
