Dielectric Tunability of DNA Biopolymer Films with Varying Amounts of Hexadecyltrimethylammonium Chloride

• Published in: Journal of electronic materials Vol. 42; no. 3; pp. 463 - 469
• Main Authors: Aga, Roberto S., Telek, Brian A., Lombardi, Jack P., Heckman, Emily M., Bartsch, Carrie M.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2013; Springer; Springer Nature B.V
• Subjects: Biopolymers; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Deoxyribonucleic acid; Dielectric properties; Dielectric thin films; Dielectrics, piezoelectrics, and ferroelectrics and their properties; DNA; Electric fields; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Optical and Electronic Materials; Physics; Solid State Physics; Surfactants; dielectric tunability; DNA biopolymer; varactor; microwave; Wave absorption; Microwave radiation; Organic solvents; Thick films; Rough surfaces; Surfactants; Surface states; Thin films; Transmission lines; Chlorides; DNA; Electric field effects; Modulation; Biopolymer; Dielectric thin films; Capacitance; Permittivity
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-012-2347-4

Deoxyribonucleic acid (DNA) biopolymer films are fabricated with varying amounts of hexadecyltrimethylammonium chloride (CTMA), which is a surfactant necessary to produce a DNA complex that is soluble in organic solvents. The dielectric constant ( κ ) of these films at microwave frequencies as a function of applied static electric field ( E DC ) is investigated. Results show that the dependence of κ on E DC , which is referred to as the dielectric tunability, is influenced by the amount of CTMA in the complex. Dielectric tunability is suppressed when the amount of CTMA is insufficient and improved when more CTMA is added. However, excessive amounts of CTMA also result in a very rough film surface that causes shorting problems when used in a capacitive structure. A varactor employing a 1- μ m-thick DNA biopolymer film as the dielectric is demonstrated. Under 5 V DC bias, which generates E DC  = 5 V/ μ m, its capacitance at 15 GHz changes by 0.04 pF. This change corresponds to a relative dielectric tunability of 6.6%. A simple application of this varactor for modulation of the power transmitted through a microwave transmission line is also demonstrated.