Enhanced optical properties due to indium incorporation in zinc oxide nanowires

Abstract

Indium-doped zinc oxide nanowires grown by vapor-liquid-solid technique with 1.6 at. % indium content show intense room temperature photoluminescence (PL) that is red shifted to 20 meV from band edge. We report on a combination of nanowires and nanobelts-like structures with enhanced optical properties after indium doping. The near band edge emission shift gives an estimate for the carrier density as high as 5.5 Â 10 19 cm À3 for doped nanowires according to Mott's critical density theory. Quenching of the visible green peak is seen for doped nanostructures indicating lesser oxygen vacancies and improved quality. PL and transmission electron microscopy measurements confirm indium doping into the ZnO lattice, whereas temperature dependent PL data give an estimation of the donor and acceptor binding energies that agrees well with indium doped nanowires. This provides a non-destructive technique to estimate doping for 1D structures as compared to the traditional FET approach. Furthermore, these indium doped nanowires can be a potential candidate for transparent conducting oxides applications and spintronic devices with controlled growth mechanism. V

Indium Dopant Concentration Effects on Zinc Oxide Nanowires

“…For our case, when we kept the indium concentration to 1.6 at. % level (as reported in our previous study), In 2 O 3 tends to act as a dopant in ZnO, resulting in insignificant change in band gap but enhanced luminescence. Increasing the concentration to higher values tends to form indium–zinc oxide alloys, resulting in shifting of wavelength more toward edge of visible region.…”

“…It is well-known that as-grown ZnO nanowires have two main emission bands: one due to the excitonic emission is found in the UV range whereas the second in the visible region related mainly due to oxygen vacancies or zinc interstitial defects. 8 To explore on the impacts of adding indium in ZnO, we characterized their optical properties and did a defect state analysis at room temperature using PL studies. PL is a nondestructive powerful tool for investigating the doping effects on the optical properties of ZnO nanowires.…”

“…In this regard, indium (In) as an alternative to these materials possess better resistivity to oxidation along with lesser reactivity as compared to aluminum, making it a much better candidate for doping in ZnO. In our previous work, we have reported indium-doped ZnO nanowires to have enhanced optical properties and paved the way forward for them to be a potential candidate for TCO and spintronic applications …”

“…In our previous work, we have reported indium-doped ZnO nanowires to have enhanced optical properties and paved the way forward for them to be a potential candidate for TCO and spintronic applications. 8 In this regard, a critical issue is the content of indium in zinc oxide that must be carefully controlled and monitored for the material to act as an efficient TCO. Philips et al, 9 Kim et al, 10 Yousefi et al, 11 and a few other researchers have shown indium concentration effects on morphology and optical properties; however, the characterization is based on either calculating the pseudodielectric functions of In-doped ZnO or measuring the absorption coefficients with respect to frequency variations.…”

Using Different Ions in the Hydrothermal Method to Enhance the Photoluminescence Properties of Synthesized ZnO-Based Nanowires

“…However, as the Eu(NO 3 ) 2 -6H 2 O or In(NO 3 ) 2 -6H 2 O are used as the dopants of ZnO-based nanowires and the hydrothermal method is used to synthesize the Eu-doped and In-doped ZnO nanowires, their emission intensities of PL spectra are really enhanced. When In is used as dopant in ZnO nanowires, an enhancement in near-band-edge emission peak (located at around 395 nm) occurs than for pure ZnO nanowires while visible-light emission is decreased significantly owing to change in the growth kinetics due to In supply which helps to reduce the number of defect states resulting in improved crystal quality [29]. XRD patterns in Figures 5 and 6 show that the 100 • C-grown undoped ZnO nanowires had high crystal quality and the crystal qualities of the 60 • C-grown ZnO-40-Eu and 88 • C-grown ZnO-4-In nanowires were higher than that of 100 • C-grown undoped ZnO nanowires.…”