Photoluminescence study of p-type vs. n-type Ag-doped ZnO films

Abstract

Silver doped ZnO films have been grown on sapphire (0001) substrates by pulsed laser deposition.Hall measurements indicate that p-type conductivity is realized for the films deposited at 500 C and 750 C. Transmission electron microscopy images show more obvious and higher density of stacking faults (SFs) present in the p-type ZnO films as compared to the n-type films. Top view and cross sectional photoluminescence of the n-and p-type samples revealed free excitonic emission from both films. A peak at 3.314 eV, attributed to SF emission, has been observed only for the n-type sample, while a weak neutral acceptor peak observed at 3.359 eV in the p-type film. The SF emission in the n-type sample suggests localization of acceptor impurities nearby the SFs, while lack of SF emission for the p-type sample indicates the activation of the Ag acceptors in ZnO.

Characteristics of Ag Doped ZnO Thin Films Prepared by Sputtering Method

“…The lowest resistivity of 1.810 -3 Ω.cm is achieved for sample doped with 2% of Ag. The low resistivity of Ag doped ZnO thin films in this research is very promising when compared with other reports [9][10][11][12][13][14] an open the possibility for using as transparent electrode in optoelectronic field.…”

“…Ag doped ZnO (ZnO:Ag) shows both n and p type conduction, depending on Ag location in ZnO crystal lattice [9]. A substitution of Ag + at Zn 2+ site will create shallow acceptor, making ZnO a p-type semiconductor.…”

“…Using PLD method, Guptan [10] prepared n-type ZnO:Ag thin film with resistivity of 310 -3 Ωcm. Myers [9] produced 2 types of ZnO:Ag thin film: n-type with resistivity of 2 Ω.cm and p-type with resistivity of 200 Ω.cm. Kim [11] reported the success of fabricating p-type ZnO:Ag thin film with resistivity of 7.2510 -2 Ω.cm by MBE technique.…”

Characterization of Ag:Zno Thin Films and Their Use in Photoelectrocatalytic Degradation Of Methylene Blue (Mb)

“…Because Ag+ ions have larger ionic radius (0.122 nm) than Zn2+ (0.074 nm), they either substitute ions of Zn2+ leading to the distortion of unit cell or segregate at the grain boundaries of ZnO and hence induced considerable distortion and faster growth of ZnO grains (Khomchenko et al, 2007;Seetawan et al, 2011). Ag+ would preferentially choose to site in the vicinity of grain boundaries due to its larger radius (Myers et al, 2015). The intensity of the ZnO (002) plane increases with Ag until 3 At % and then decreases with further increase of the Ag which suggest that 3 At % Ag doping can enhance the ZnO (002) preferential orientation but excess Ag doping will deteriorate it.…”

ZnO thin films grown at different plasma energies by the laser ablation of metallic Zn with a 532 nm wavelength

“…In the literature it has been reported, for ZnO thin films, photoluminescence (PL) emissions, at RT, in the UV range (around 377 nm) [4], in the visible range (400 to 700 nm) or in both [5]. PL emissions in the UV range are associated with band to band recombination (electrons and holes) [6]. While emissions in the visible region are associated with defect carrier concentrations: donor (zinc interstitial Zn i and oxygen vacancies V O ) and acceptors (Zinc vacancies V Zn and oxygen interstitial O i ) [7].…”