Physical and Analytical Chemistry Seminar
Lecturer: Mohammed Attrash Schulich Faculty of Chemistry, Technion
Location: Join Zoom Meeting at https://technion.zoom.us/j/98640529463
Diamond has attractive chemical and physical properties, thus it has been used in different applications and technologies. To functionalize diamond samples for different applications, surface termination by different atoms while minimizing the damage level is essential. For example, terminating the diamond surface with nitrogen or oxygen atoms may lead to positive electron affinity, while terminating diamond surface with hydrogen atoms leads to negative electron affinity. In this seminar, I will present the chemical and physical properties of different diamond surfaces ((100) and (111) single crystal diamond and polycrystalline diamond surfaces) exposed to nitrogen plasma (N-diamond). The nitrogen molecules were activated by two plasma frequencies: microwave (MW) and radio frequency (RF). Initially, we identified the different particles (charged or radical nitrogen molecules) that are present in the nitrogen plasma by using optical emission spectroscopy. This step is important to identify the source of the damage caused to the diamond surface. Then we investigated the nitrogen chemical bonding, nitrogen concentration, work function, and structure properties of N-diamond by different surface electron spectroscopic methods, such as X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively), low electron energy diffraction (LEED), and high resolution low electron energy spectroscopy (HREELS). Beside the experimental tools, density functional theory was used to model the N-diamond (111) surface. The nitrogen concentration and its thermal stability on the diamond (100) surface are different than that of diamond (111) after exposing to the same nitrogen plasma conditions. The MW(N2) plasma in my study revealed lower damage level than the RF(N2) plasma. However, in the case of RF(N2) plasma, the damage level can be controlled by changing the nitrogen gas pressure.
This research was conducted under the supervision of
Prof. Alon Hoffman