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“Growth and characterization of phosphorus doped n-type CVD diamond films of various orientations and devices/applications based on these”

  The fact that diamond is a fabulous material with special properties, which are explored in wide range of applications, is already known by now. The aim of this thesis is to exploit the material’s characteristics, namely the semiconducting property. The deposition and characterization of n-type Chemical Vapour Deposition (CVD) diamond thin films are presented first in this study. The bottom-up approach used in this survey starts with the description of the growth procedure of phosphorus doped diamond using a commercially available microwave plasma enhanced CVD system (ASTeX). The process uses methane (CH4), hydrogen and phosphine (PH3) as gaseous precursors. As substrates different substrate materials were used starting with single crystalline HPHT diamond substrates, continuing with polycrystalline diamond and finishing with non-diamond substrates, such as molybdenum metallic plates. The influence of diamond substrate orientation on the obtained films is widely discussed.

Structural, morphological as well as advanced (opto-)electrical characterization were carried out with the techniques available at IMO-IMOMEC and at our collaborators. After a careful evaluation of the obtained results it was established that qualitative P-doped diamond films can be obtained. In the attempt to improve the quality layers a new set of doping plasma parameters was proposed and tested.

Based on the results provided from the doping of different diamond substrates, the fabrication of high quality devices is presented at the end of this survey. The simplest application, which makes use of the semiconducting properties of diamond, is the “pn-junction”, which is the main device being addressed in this work. The thesis ends with an extension of the range of diamond-based devices, thus presenting thermionic electron emission measurements of the polycrystalline P-doped films grown on metallic substrates.