|M.Sc Student||Michaelson Shaul|
|Subject||Deposition and Electron Emmision Properties of Sub-micron|
Thick Polycrystalline Diamond Films
|Department||Department of Chemistry||Supervisor||Professor Alon Hoffman|
In this work we have deposited, characterized and investigated electronic properties of sub-micron thick and continuous polycrystalline diamond films and membranes grown by conventional hot filament chemical vapor deposition (HF CVD) method on Silicon substrates. Diamond nucleation was promoted by mechanical abrasion of the substrate by ultrasonic treatment in a slurry consisting of a mixture of small diamond particles (< 0.25 mm) and larger metal or diamond particles (40-100 mm). This pretreatment results in a primary diamond particle density (DPD) of ~5´1010 cm-2. Free-standing diamond membranes of sub-micron thickness were prepared by etching the underlying silicon substrate. The structural, morphological and electronic properties of such membranes were investigated.
Electron emission properties of sub-micron thick films and free-standing membranes were studied by means of absolute quantum photoyield (QPY) and ion-induced electron emission (IIEE) as a function of film thickness and surface conditioning. Absolute QPY measurements were carried out for photon energies in the range of 140-220 nm (8.9-6.2 eV). IIEE measurements were performed with 140 keV Argon and 200 keV Hydrogen ions as function of ion dose. Both the IIEE and QPY increase with film thickness, go through a maximum at values of 60-120 nm and reach nearly constant values for thicker films. The highest IIEE values in the case of Hydrogen and Argon ion irradiation measured were 58 and 116 electrons/ion correspondingly. The highest absolute QPY measured was 14 % for an incident wavelength of 140 nm.