Defect-Engineered Graphene Devices for Electronic DNA Sequencing – DFT and NEGF Studies

Graphene, a low-dimensional material, has shown significant promise in bioelectronics over the past two decades. Most research in this field has focused on pristine graphene. However, experimentally fabricated two-dimensional (2D) graphene and one-dimensional (1D) graphene nanoribbons (GNRs) often contain impurities, such as Stone−Wales (sw) and divacancy (dv) defects. In this study, we conducted a comparative computational analysis of the adsorption behavior of DNA nucleobases−adenine (A), guanine (G), thymine (T), and cytosine (C) on three types of graphene nanoribbon (GNR) surfaces: pristine (prGNR), divacancy-defected (dvGNR), and Stone−Wales-defected (swGNR). We modeled the influence of nucleobase adsorption on the current-voltage (I-V) response of pristine and defected graphene nanoribbon devices using the Non-Equilibrium Green’s Function (NEGF) method. Our results show that dvGNR devices exhibit the highest current sensitivity and the most distinct I-V responses across different nucleobases, making it particularly effective for nucleobase detection. While prGNR devices can detect certain nucleobases, they perform less consistently due to proportional current increases with higher biases, leading to similar trends. In contrast, swGNR devices successfully distinguish all four nucleobases through distinct current signals observed between 0.6 and 0.8 V applied biases. These findings are crucial for the development of sensitive biosensing technologies.