טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentTordjman Moshe
SubjectSurface Transfer Doping of Diamond and Ultrananocrystalline
Diamond:
Science and Potential Applications
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisors Professor Emeritus Rafael Kalish
Dr. Cecile Saguy
Full Thesis textFull thesis text - English Version


Abstract

Diamond have outstanding physical assets and fascinating chemical and optical properties. Its surface exhibits a negative electron affinity when hydrogen terminated and when further exposed to a surface acceptor, i.e. humidity (H2O), a surface transfer doping takes place leading to a two dimensional p-type surface conductivity. These make diamond a material of choice for application in electrical devices. Furthermore, the fact that diamond films in the form of single crystal, polycrystalline and nano-sized diamond crystallites embedded in amorphous carbon (referred to as Ultra Nano Crystalline Diamond films) can be grown and modified by Chemical Vapor Deposition (CVD), raised up many scientific and technological interests.

In this work we study the electrical properties of the surface transfer doped UNCD thin film. UNCD:H/H2O films were found to exhibit unique electron field emission characteristics, consisting of a reversible switch-memory effect. This new electron field emission effect observation has been experimentally studied in function to temperatures and modelled by a double barrier resonant tunneling formed by the outermost ta-C/Nanodiamond/H2O/Vacuum heterostructure.

            An additional stratum of this work suggests a new material for replacing the thermally unstable H2O molecule inducing the two dimensional electrical conductivity of diamond:H by its surface transfer doping. Diamond transfer doping has been achieved using a Molybdenum Trioxide (MoO3) as a novel acceptor candidate yielding a p-type conductive diamond surface with highest yet reported sheet conductivity and unsurpassed thermal stability.