Sensing properties of deformed graphene nanoribbon through warping

Abstract

Semiconductor materials have become the fundamental building block in the design of gas sensor. Previous researchers work on gas sensor that recognized its limitations such as low binding energy, low sensitivity and poor selectivity. As an alternative, considerable interests have generated in carbon based material like graphene to improve the sensing device performance. The purpose of this study is to investigate the sensing behaviour of deformed armchair graphene nanoribbon (AGNR) through warping using Extended-Huckel Theory (EHT) coupled with Non- Equilibrium Green Function (NEGF). The AGNR are warped upward and inward at angles of 180o, 270o and 360o. The sensing properties are measured for oxygen (O2) and ammonia (NH3) molecules, particularly on their binding energy, charge transfer and sensitivity. Generally, inward warped AGNR shows better performance compared to upward deformation. Three AGNR configurations have been investigated; 3m, 3m+1 and 3m+2, where m known as an integer. Performance of each AGNR configuration behaves differently with the applied warping. Simulation results have indicated that for upward 3m configuration, the warping AGNR exhibit 98% enhancement in binding energy when warped at 360o for NH3 molecule. While for 3m+1 and 3m+2 the binding energy exhibit 72% and 64% improvement respectively. The same trend of observation is achieved for O2 molecules. The results obtained also discovered a chemisorption in 3m, 3m+1 and 3m+2 configuration for both O2 and NH3. For 3m and 3m+1 configurations, the sensitivity has been observed at twoorder of magnitude for higher warping angles, which most previous studies have not achieved. Meanwhile, negative sensitivity is observed in 3m+2 configuration. The marked improvement of the warped AGNR sensing properties is attributed from the combination of strain and curvature effect. The warping can also be an alternative method to minimize drawbacks in traditional gas sensors. The sensitivity of gas sensor could be enhanced by introducing the warped AGNR.