Hassel and Marianne Ledbetter MatSE Colloquium - "New developments in ultrawide bandgap materials and their processing by low-temperature plasmas"
- Sponsor
- Materials Science and Engineering Department
- Speaker
- Prof. R. Mohan Sankaran, Department of Nuclear, Plasma, and Radiological Engineering, UIUC
- Contact
- Bailey Peters
- bnpeters@illinois.edu
- Originating Calendar
- MatSE Colloquium Calendar
Ultrawide bandgap materials such as diamond and hexagonal boron nitride (hBN) are a class of semiconductors with bandgaps in excess of ~5 eV that are desired for high-power, extreme environment, and ultraviolet applications. While these materials have been been studied for many decades now, new properties continue to be unearthed because of synthetic challenges, advances in measurement tools, and emerging technologies.
In this talk, I will present two efforts, one related to diamond and the other related to hBN. First, we have recently discovered intervalence band plasmons in boron-doped diamond, defined as collective electronic excitations between the valence subbands. To probe these low-energy (<0.5 eV) transitions, we applied several relatively advanced techniques, including scanning transmission electron microscopy-valence electron energy loss spectroscopy (STEM-VEELS) and scanning near-field optical microscopy (SNOM), and carried out first-principle calculations. Second, we have developed a plasma-based process to deposit hBN which allows direct growth (i.e. transfer-free) on silicon and glass substrates for electronic and optical applications. Mechanistic insight is obtained by infrared spectroscopic characterization of the deposited films under different processing conditions including controls. Third and finally, optically-active defects are introduced into hBN by plasma irradiation. We use a remote plasma that minimizes microscale damage, making it possible to fabricate quantum emitters in monolayers.