Modulating Electronic Structures of Armchair GaN Nanoribbons by Chemical Functionalization under an Electric Field Effect

Abstract

The electronic and magnetic properties of oxygen-and sulfur-passivated one-dimensional armchair GaN nanoribbons (A-GaNNRs) are revealed using both firstprinciples density-functional theory and ab initio molecular dynamics simulations. We explore that an applied external electric field can further modulate the electronic properties of both pristine and passivated A-GaNNRs, thus changing their properties (semiconducting−metallic−half-metallic). A-GaNNRs of 0.9−3.1 nm width are subjected to further investigations, which reveal that sulfur termination transforms pristine A-GaNNRs from direct into indirect band gap semiconductors, without affecting their nonmagnetic nature. On the other hand, oxygen passivation introduces spin-polarized behavior with a finite magnetic moment. Magnetism characteristics in both bare and sulfur-passivated A-GaNNRs are induced by applying a critical electric field along the direction of NR width. The passivated A-GaNNRs are more stable compared to bare ones, while sulfur-passivated A-GaNNRs exhibit higher stability at higher temperatures (>500°C). Thus, our results suggest that A-GaNNRs can be used in a broad range of electronic, optoelectronic, and spintronic applications.

Strain-Engineering of Electronic and Magnetic Properties of Chemically Passivated Zigzag GaN Nanoribbons: An Ab Initio Study

“…Moreover, the spin-density plot shown in the right panel of Figure c indicates that the magnetic contribution comes from the S N atoms and edge N atoms. This behavior is similar to that which we previously reported for S-A-GaNNRs . The O passivation of Z-GaNNRs results in two possibilities of electronic structures, half-metal and semiconductor properties, inducing both FM and AFM, respectively.…”

“…As Z-GaNNRs of 6–10 N z width exhibited similar electronic and magnetic properties (see Figure S1 in Supporting Information), in this study, we focus on N z = 6. Similar behavior was also reported for A-GaNNRs . The crystal structures of bare and O- and S-passivated Z-GaNNRs are presented in Figure a–c for bare and passivated Z-GaNNRs of N z = 6 width.…”

“…The AFM phase occurs as the spin-up and spin-down channels overlap; in this case, the material becomes a semiconductor with a bandgap of 0.24 eV, as shown in Figure c. Similar behavior was also predicted for the O-passivated A-GaNNRs in the AFM state by our previous calculations . To elucidate the magnetic behavior of O-Z-GaNNRs, we study its PDOS.…”

“…The δG hierarchy is preserved for all widths, i.e., Z-GaNNR > S-Z-GaNNR > O-Z-GaNNR, and a similar trend was also reported for A-GaNNRs. 41 The greater stability of O-passivated GaNNRs can be due to the fact that the atomic size of O is closer to that of N, while O has higher electronegativity compared to S. Therefore, the formation energy of Ga−O bonding is lower than that of Ga−S bonding, as shown in Table 1.…”

“…Similar behavior was also reported for A-GaNNRs. 41 The crystal structures of bare and O-and S-passivated Z-GaNNRs are presented in Figure 1a−1c for bare and passivated Z-GaNNRs of N z = 6 width. For the optimized structures after relaxation, a Ga−N bond length of 1.86 Å was obtained in the inner region of all NR structures.…”