The main goal of this research was to maintain the bulk charge carrier mobility of graphene, after deposition of the gate dielectric layer used for making transistor devices. The approach was introducing a thin film of deoxyribonucleic acid (DNA) nucleobase purine guanine, deposited by physical vapor deposition (PVD), onto layers of graphene that were transferred onto various flexible substrates. Several test platforms were fabricated with guanine as a standalone gate dielectric, as the control, and guanine as a passivation layer between the graphene and PMMA. It was found that the bulk charge carrier mobility of graphene was best maintained and most stable using guanine as a passivation layer between the graphene and PMMA. Other transport properties, such as charge carrier concentration, conductivity type and electrical resistivity were investigated as well. This is an important first step to realizing high performance graphene-based transistors that have potential use in bio and environmental sensors, computer-processing and electronics.
Many papers have been published on the properties of deoxyribonucleic acid (DNA) and DNAhexadecyltrimethylammonium
chloride (CTMA) and their applications in electronics and photonics. This paper is a
review of some of the properties and their related applications for other types of naturally occurring materials,
nucleic acid bases or nucleobases which make up the DNA molecules. Nucleobases under investigation included
guanine, cytosine, adenine and thymine. Potential applications include electron blocking layers for organic light
emitting diodes, gate dielectrics for organic thin film transistors and protective layers for polymer-based capacitors.
In this study, we investigated the effect of substrates on the electrical properties of transferred graphene. A wide range of substrates such as silicon carbide (SiC), glass, kapton, photo-print paper, polydimethylsiloxane (PDMS) and Willow glass were selected based on their surface properties, flexibility and lattice match. Four monolayers of graphene were transferred onto each of these substrates. A comparative study of the electrical characteristics of the transferred graphene film only and graphene/guanine film on the different substrates was undertaken.
This paper is a review of the recent research in bio-based materials for photonics and electronics applications. Materials
that we have been working with include: deoxyribonucleic acid (DNA)-based biopolymers and nucleobases. We will
highlight work on increasing the ionic conductivity of DNA-based membranes, enhancing the direct (DC) current and
photoconductivity of DNA-based biopolymers, crosslinking of DNA-based biopolymers and promising applications for
In this study, we investigate a new technique to fabricate DNA-CTMA films with tunable properties. MAPLE is, for the first time, explored to deposit DNA-CTMA dielectric films on top of epitaxially grown graphene on silicon carbide (SiC) substrate. Silicon dioxide (SiO<sub>2</sub>) is commonly used as a gate insulator in graphene based field effect transistors (GFETs) in a top gate configuration. The high temperature deposition of SiO<sub>2</sub> on graphene is known to cause damage to the surface of the graphene leading to poor device operation. We propose an alternative gate insulator based on a bio-organic (DNA-CTMA) material processed and deposited at room temperature (RT) using MAPLE. Hall measurements run before and after DNA-CTMA deposition showed no change in the type of conductivity as well as charge carrier mobility.
In previous research we have demonstrated improvements in device performance with the incorporation of a deoxyribonucleic acid (DNA)-based biopolymer into organic light emitting diodes, organic thin film transistors and other organic photonic and electronic devices. Here, we investigate nucleobases, nitrogen-containing biological compounds found within DNA, ribonucleic acid (RNA), nucleotides and nucleosides, for use in a few of those previously investigated photonic and electronic devices. Used as an electron blocking layer in OLEDs, a gate insulator for grapheme transistors and as a dielectric in organic-based capacitors, we have produced comparable results to those using DNA-based biopolymers.