Zur Machbarkeit adressierbarer Nanolöcher in einer Festkörpermembran
Auch gedruckt in der BibliothekW: W-H 15.157
FakultätFakultät für Naturwissenschaften
InstitutionInstitut für Experimentelle Physik
Institut für Festkörperphysik
Ressourcen- / MedientypDissertation, Text
Datum der Erstveröffentlichung2017-06-28
This thesis was created in the context of the project A3 "Integration of Pore Proteins into Electronic Nanostructures for Biosensing" which is part of the "Kompetenznetz Funktionelle Nanostrukturen" funded by the Baden-Württemberg Stiftung. The objective of the project is the preparation and investigation of hybrid membranes as biosensors, consisting of biological pores and silicon-rich nitride membranes with electric contacting. This thesis is dedicated to the preparation and characterization of membrane chips with adjustable pore size which will subsequently enable the integration of pore proteins. Two types of process control for the preparation of membrane chips on the nanoscale were investigated. These procedures are on the one hand a FIB-based method and on the other hand a more sophisticated process based on the micellar and RIE technique. Membrane chips with up to 8 individual control contacts and 8~nanoholes were realized with the FIB-based process control and proven by SEM. By feasibility study investigating the micellar technique based procedure it was shown that this procedure is not suitable for generating membrane chips with the available equipment. For the experiments the membrane chips were fabricated using the FIB-based process control. A special measurement chamber was designed and built to investigate the ion current through the nanoholes on the membrane chips as a function of the control potential on the contacts. Further parts of the measurement setup were a custom-built potential switcher and a patch clamp amplifier. The operational capability of the measurement chamber and its potential to detect ion currents in the pico- to nanoampere range was successfully verified. Measurements of membrane chips with applied control potentials show that despite an additional ALD deposited alumina insulating layer the resistance was still too low to avoid leak currents which influence the measured ion current. Calculations with the specific conductivity of the bulk material point out sufficiently high resistance. In this subject area further quality improvements of the existing ALD process are necessary, which is a separate and complex issue. The unpreventable implantation of gallium in the silicon-rich nitride hole wall during the preparation of the nanoholes using FIB supposedly results in the observed, complex behavior of the leak current. The production of single pores without switch contacts or small arrays of such pores via FIB is not an issue [38-41]. The FIB-based process control has limitations for high requirements with respect to the electrical properties as in this case. RIE or wet etch technique based preparation technologies are certainly more suitable for the fabrication of the nanoholes. Further studies should concentrate on this approach.