TECHNICAL PAPER Metal to semiconductor conversion by hydrogenation in guanine functionalized SWCNT Swati Sinha 1 • Jaya Bandyopadhyay 1 Received: 15 August 2017 / Accepted: 11 January 2018 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Conversion of the metallic SWCNT to semiconducting SWCNT was achieved by band structure engineering of the nanotube by functionalization of the DNA nucleobase, guanine. The band structure analysis revealed that metallic SWCNT (6, 0), when surface engineered with guanine nucleobase with H-atom attachment as the functional group, is converted to a semiconductor one by opening a narrow bandgap with a value of 0.08 eV. This phenomenon was brought about by strong chemisorption due to hydrogenation by inducing partial sp 3 hybridization in the nanotube structure. No bandgap openings were observed when guanine was adsorbed on the pristine nanotube surface by its nitrogen site and oxygen site respec- tively. Related zero-bias transmission spectra and IV-curve supported the result also. The entire study was done at room temperature using ATK-VNL simulation software. 1 Introduction For the past few years single-walled carbon nanotubes (SWCNTs) have drawn the attention of entire research activity of nanotechnology for their diverse and unique physical and chemical properties which are exploited in different technological areas (Gomez et al. 2009; Thostenson et al. 2001; Avouris et al. 2007; Mahar et al. 2007) like field emitters (De Heer et al. 1995; Chung et al. 2000), transistors (Cheng and Samulski 2004; Collins et al. 2001), gas sensors (Modi et al. 2003; Kong et al. 2000), supercapacitors (Frackowiak and Beguin 2001; Emmenegger et al. 2003; An et al. 2001) and nanoprobes (Kim and Lieber 1999) including various biomedical applications (Shi Kam et al. 2004; Esser et al. 2012; Cheung et al. 2010; Sinha and Yeow 2005). Functional- ization of sidewall (Hu et al. 2003) of SWCNT with hydrophilic biomolecules like DNA (deoxyribonucleic acid) or even DNA nucleobase can alter (Nicolas 2014) the electronic property of the nanotubes (Bachrach 2007) by conversion of the metallic property of SWCNT to a semiconductor one for various applications in molecular electronics, nano- and opto-electronics, sensor designing and nanomedicine (Perdew et al. 1996). SWCNT is made up of by folding a single layer of cylindrical graphene sheet with diameter ranging from 0.4 to 2.0 nanometre having ultra-light weight, high aspect ratio (length:diame- ter = 132,000,000:1), high mechanical strength (200 Giga Pascal), high electrical conductivity (4 9 10 9 A/cm 2 ) and thermal conductivity (Garcia-Sanchez et al. 2008). SWCNT can be a metal with no bandgap or semiconductor with bandgap value ranging from 0.5 eV to 10 meV (Pan et al. 2009). Guanine is one of the four DNA nucleobases containing a fused pyrimidine-imidazole ring with conju- gated double bonds. In DNA double-helix, guanine is paired with cytosine by three hydrogen bonds (Yi et al. 2008). 2 Related work Functionalization of CNT (carbon nanotube) can transform the electronic structure of m-SWCNT (metallic single- walled carbon nanotube) to s-SWCNT (semiconducting single-walled carbon nanotube) by inducing a partial sp 3 hybridization (Fagan et al. 2003; Tournus and Charlier 2005) which can be achieved by strong chemisorption by hydrogenation and fluorination (Perdew et al. 1996). & Swati Sinha sinhaswati44@gmail.com Jaya Bandyopadhyay jaya.bandyopadhyay@gmail.com 1 Department of Biotechnology, Maulana Abul Kalam Azad University of Technology, West Bengal, Kolkata, West Bengal 700064, India 123 Microsystem Technologies https://doi.org/10.1007/s00542-018-3723-7