Effects of Ag-induced acceptor defects on the band gap tuning and conductivity of Li:ZnO films

Abstract

The effects of Ag-induced acceptor defects on the band gap tuning and conductivity of Li:ZnO film grown by the sol-gel method were investigated. The structural analyses indicate that the Ag-Li:ZnO films possess hexagonal structure with the substitutional Ag defect at the Zn site (AgZn) and the interstitial Li defect (Lii). The decreased film transmittance and band gap with Ag-Li codoping is mainly due to the incorporation of foreign impurity levels by the AgZn and Lii defects. The electrical measurements reveal that doping can obviously improve the film conductivity, which could be attributed to the reduction of the grain boundary scattering and the inter-diffusion of the Ag nanoparticles, as well as the decreased ionization energy of the acceptor owing to the AgZn defects. The electronic structures of Ag-Li:ZnO were further studied by the first-principles calculations and the results show that the AgZn defects may lead to p-type conductivity of ZnO.

Ag/ZnO nanoparticles thin films as visible light photocatalysts

“…The particle size measured from SEM however appeared to be slightly greater than that calculated from XRD results therefore it can be assumed that the particles appearing in SEM are result of aggregation of small crystallites. Excess silver nanoparticles also appear as white clusters as reported by other studies by assembling at grain boundaries and aggregating into cluster form 41,42 as conrmed from the XRD data of Ag (111) plane. The morphology of Ag nanoparticles also changed from ake like to cylindrical particles with the increase in substrate temperature from RT to 100 C as illustrated in Fig.…”

Heterojunction Nanowires of AgxZn1–xO–ZnO Photocatalytic and Antibacterial Activities under Visible-Light and Dark Conditions

“…Moreover, by increasing the Ag acceptors in ZnO nanowires, Figure a further reveals that the intensity of the Zn 2p 3/2 and Zn 2p 1/2 has significantly decreased, while the intensity of Ag 3d 5/2 and Ag 3d 3/2 obviously increased (see Figure b). The Ag atoms prefer to occupy the Zn sites and act as acceptors because the formation energy of Ag Zn is lower than that of the Ag i . ,, As a result of these strong evidence, the Ag acceptors were formed as a primary Ag Zn state for ZnO nanowires and constituted the Ag x Zn 1– x O–ZnO (i.e., Ag zn -related compound) heterojunction nanowires. Thus, the low temperature of UV decomposition process provides a prospective method to achieve the incorporation of Ag acceptors in ZnO nanowires.…”

“…The Ag x Zn 1−x O−ZnO nanowires exhibited a significant red-shift effect in contrast to that of the pristine ZnO nanowires, implying that the Ag x Zn 1−x O−ZnO nanowires possess a photocatalytic activity under visible-light illumination.The Ag acceptors in ZnO nanowires may form impurity bands instead of the formation of Ag nanoclusters on the ZnO nanowires' surface. Moreover, the Ag Zn defects can lead to ptype semiconductor of ZnO 22. To understand the defect levels of the nanowires, photoluminescence spectroscopy was used to investigate the emission bands of the ZnO and Ag x Zn 1−x O−…”

Ab-initio study of donor-acceptor codoping for n-type CuO

“…[7][8][9][10] Theoretically, Yamamoto et al first proposed codoping with acceptor and donor (2:1 for p-type and 1:2 for n-type) to realize low-resistivity p-type ZnO 11 and GaN. 12 In this case, defect association occurs due to the Columbic attraction between n-and p-type dopants with opposite charges.…”