Investigation of electrically active defects at the interface of high-k dielectrics and compound semiconductors

O'Connor, Éamon

Investigation of electrically active defects at the interface of high-k dielectrics and compound semiconductors

dc.check.embargoformat	Both hard copy thesis and e-thesis	en
dc.check.entireThesis	Entire Thesis Restricted
dc.check.opt-out	Not applicable	en
dc.check.reason	This thesis is due for publication or the author is actively seeking to publish this material	en
dc.contributor.advisor	Hurley, Paul K.	en
dc.contributor.author	O'Connor, Éamon
dc.contributor.funder	Science Foundation Ireland	en
dc.date.accessioned	2016-08-24T10:18:27Z
dc.date.issued	2014
dc.date.submitted	2014
dc.description.abstract	As silicon based devices in integrated circuits reach the fundamental limits of dimensional scaling there is growing research interest in the use of high electron mobility channel materials, such as indium gallium arsenide (InGaAs), in conjunction with high dielectric constant (high-k) gate oxides, for Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) based devices. The motivation for employing high mobility channel materials is to reduce power dissipation in integrated circuits while also providing improved performance. One of the primary challenges to date in the field of III-V semiconductors has been the observation of high levels of defect densities at the high-k/III-V interface, which prevents surface inversion of the semiconductor. The work presented in this PhD thesis details the characterization of MOS devices incorporating high-k dielectrics on III-V semiconductors. The analysis examines the effect of modifying the semiconductor bandgap in MOS structures incorporating InxGa1-xAs (x: 0, 0.15. 0.3, 0.53) layers, the optimization of device passivation procedures designed to reduce interface defect densities, and analysis of such electrically active interface defect states for the high-k/InGaAs system. Devices are characterized primarily through capacitance-voltage (CV) and conductance-voltage (GV) measurements of MOS structures both as a function of frequency and temperature. In particular, the density of electrically active interface states was reduced to the level which allowed the observation of true surface inversion behavior in the In0.53Ga0.47As MOS system. This was achieved by developing an optimized (NH4)2S passivation, minimized air exposure, and atomic layer deposition of an Al2O3 gate oxide. An extraction of activation energies allows discrimination of the mechanisms responsible for the inversion response. Finally a new approach is described to determine the minority carrier generation lifetime and the oxide capacitance in MOS structures. The method is demonstrated for an In0.53Ga0.47As system, but is generally applicable to any MOS structure exhibiting a minority carrier response in inversion.	en
dc.description.sponsorship	Science Foundation Ireland (SFI Grant 07/SRC/I1172 FORME, SFI Grant 09/IN.1/I2633 INVENT)	en
dc.description.status	Not peer reviewed	en
dc.description.version	Accepted Version
dc.format.mimetype	application/pdf	en
dc.identifier.citation	O'Connor, E. 2014. Investigation of electrically active defects at the interface of high-k dielectrics and compound semiconductors. PhD Thesis, University College Cork.	en
dc.identifier.endpage	170	en
dc.identifier.uri	https://hdl.handle.net/10468/3019
dc.language.iso	en	en
dc.publisher	University College Cork	en
dc.relation.project	info:eu-repo/grantAgreement/SFI/SFI Principal Investigator Programme (PI)/09/IN.1/I2633/IE/Investigating Emerging Non-Silicon Transistors (INVENT)/
dc.relation.project	info:eu-repo/grantAgreement/SFI/SFI Strategic Research Cluster/07/SRC/I1172/IE/SRC FORME: Functional Oxides and Related Materials for Electronics/
dc.rights	© 2014, Éamon O'Connor.	en
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/	en
dc.subject	InGaAs	en
dc.subject	GaAs	en
dc.subject	MOS capacitor	en
dc.subject	High-k	en
dc.subject	Inversion	en
dc.subject	Interface states	en
dc.subject	Ammonium sulfide	en
dc.thesis.opt-out	false
dc.title	Investigation of electrically active defects at the interface of high-k dielectrics and compound semiconductors	en
dc.type	Doctoral thesis	en
dc.type.qualificationlevel	Doctoral	en
dc.type.qualificationname	PHD (Engineering)	en
ucc.workflow.supervisor	paul.hurley@tyndall.ie