Nanocrystalline diamond growth and device applications
FacultiesFakultät für Ingenieurwissenschaften und Informatik
LicenseStandard (Fassung vom 01.10.2008)
Diamond possesses such outstanding properties that its exploitation in many fields is sought for several years now. Mechanical, thermal, electrical and chemical features of diamond render it the ideal material for power electronics, chemical sensors, thermal dissipation and high temperature devices. The inadequate size of available diamond substrates, limited to few millimeters, made necessary the development of nanocrystalline (NCD) diamond, available today on large area wafers. Unfortunately NCD possesses still many unsolved problems which prevent its large diffusion and use. In this work several issues related to NCD growth are addressed, regarding especially the growth of boron doped NCD for electrochemistry and of intrinsic NCD on III-nitrides for heat sink applications. Two new NCD growth techniques are introduced. The first concerns the growth of boron delta doped NCD on silicon with suitable electrochemical properties by means of Hot Filament CVD (HFCVD). The second concerns the nucleation and the growth of NCD on InAlN/GaN at high temperature by means of HFCVD and plasma CVD using BEN (Bias Enhanced Nucleation); the NCD quality is verified by Raman spectroscopy and SEM microscopy, while the electronic features of InAlN/GaN are preserved after NCD growth. Two novel diamond based ISFET concepts are furthermore introduced. The first concept is based on oxygen terminated boron delta doped NCD and provides chemical stability and sensitivity of diamond on large area for the first time. The second concept is based on the combination of a boron doped NCD electrode with an InAlN/GaN HEMT; this device possesses all the advantages of the boron delta doped NCD ISFET, but provides higher sensitivity thanks to the outstanding electrical properties of the nitride heterostructure. The use of NCD as heat sink on power devices is explored by growing NCD on InAlN/GaN HEMTs at high temperature; the HEMT characteristics are shown to be essentially preserved after NCD growth.
Subject HeadingsNanokristall [GND]
Electrochemical sensors [LCSH]