|Ph.D Student||Laikhtman Alexander|
|Subject||Chemical and Physical Processes on Diamond Surfaces Induced|
by Low Energy Photon, Electron and Ion
|Department||Department of Chemistry||Supervisor||Professor Alon Hoffman|
Electronic properties of diamond are highly dependent on the chemical state of its surface and near-surface region and presence of defects in its crystal lattice. In particular, hydrogenated diamond films exhibit negative electron affinity which results in the enhancement of their electron emission properties. Even minor concentration of some surface adsorbates can substantially modify the response of diamond to photon and electron irradiation. However, many issues related to surface chemical bonding of diamond, its reactivity and influence of photon, electron and ion irradiation on the chemical state of adsorbates were far from being understood. In this research we have resolved a considerable part of these problems.
As-grown diamond films were exposed to different species like hydrogen and oxygen. Then, electron emission properties, response to low energy photon and electron irradiation, and chemical reactivity toward atmospheric gases of modified diamond surfaces have been studied.
We have investigated the chemical bonding and electronic properties of bare and hydrogenated diamond surfaces by a combination of various surface sensitive techniques. The interactions of these surfaces with thermally activated and molecular oxygen, as well as with ambient atmosphere and water vapor have been studied in details; the products of such interactions have been unambiguously determined. We have elucidated the response of hydrogen- and oxygen-terminated surfaces to low energy electron and photon irradiation and established the mechanism and dynamics of the processes related to these interactions. We have proved that hydrogen atoms activated by microwave plasma diffuse into bulk atomic layers in diamond. We have also found that the most effective way to remove defects induced by ion bombardment is by microwave hydrogen plasma treatment of damaged diamond.