Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Department

Electrical Engineering

First Advisor's Name

Dr. Irene Calizo

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Prof. Shekhar Bhansali

Second Advisor's Committee Title

Co-Committee Chair

Third Advisor's Name

Prof. Sakhrat Khizroev

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Dr. Frank Urban

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Dr. Nezih Pala

Fifth Advisor's Committee Title

Committee Member

Sixth Advisor's Name

Dr. Jin He

Sixth Advisor's Committee Title

Committee Member

Keywords

2D nanomaterials, graphene, silicene, germanene, boron carbide, DFT, band gap, gas sensor, Computational nanoscience, spintronics, electronic and magnetic properties

Date of Defense

6-28-2017

Abstract

The popularity of graphene owing to its unique properties has triggered huge interest in other two-dimensional (2D) nanomaterials. Among them, silicene shows considerable promise for electronic devices due to the expected compatibility with silicon electronics. However, the high-end potential application of silicene in electronic devices is limited owing to the lack of an energy band gap. Hence, the principal objective of this research is to tune the electronic and magnetic properties of silicene related nanomaterials through first-principles models.

I first explored the impact of edge functionalization and doping on the stabilities, electronic, and magnetic properties of silicene nanoribbons (SiNRs) and revealed that the modified structures indicate remarkable spin gapless semiconductor and half-metal behaviors. In order to open and tune a band gap in silicene, SiNRs were perforated with periodic nanoholes. It was found that the band gap varies based on the nanoribbon’s width, nanohole’s repeat periodicity, and nanohole’s position due to the quantum confinement effect. To continue to take advantage of quantum confinement, I also studied the electronic and magnetic properties of hydrogenated silicene nanoflakes (SiNFs). It was discovered that half-hydrogenated SiNFs produce a large spin moment that is directly proportional to the square of the flake’s size.

Next, I studied the adsorption behavior of various gas molecules on SiNRs. Based on my results, the SiNR could serve as a highly sensitive gas sensor for CO and NH3 detection and a disposable gas sensor for NO, NO2, and SO2. I also considered adsorption behavior of toxic gas molecules on boron carbide (BC3) and found that unlike graphene, BC3 has good sensitivity to the gas molecules due to the presence of active B atoms. My findings divulged the promising potential of BC3 as a highly sensitive molecular sensor for NO and NH3 detection and a catalyst for NO2 dissociation. Finally, I scrutinized the interactions of CO2 with lithium-functionalized germanene. It was discovered that although a single CO2 molecule was weakly physisorbed on pristine germanene, a significant improvement on its adsorption energy was found by utilizing Li-functionalized germanene as the adsorbent. My results suggest that Li-functionalized germanene shows promise for CO2 capture.

Identifier

FIDC001949

ORCID

orcid.org/0000-0002-0108-8994

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