We report on the growth of ZnO nanostructures in different gas ambient (Ar and N 2 ) using pulsed laser deposition technique. Despite the similar growth temperature, use of N 2 ambient gas resulted in well-aligned nanorods with flat surface at the tip, whereas, nanorods grown with Ar ambient exhibited tapered tips. The Nanorods grown under N 2 ambient exhibited additional Raman modes corresponding to N induced zinc interstitials. The nanorods are c-axis oriented and highly epitaxial in nature. Photoluminescence spectroscopy reveals that the UV emission can be significantly enhanced by 10 times for the nanorods grown under Ar ambient. The enhanced UV emission is attributed to the reduction in polarization electric field along the c-axis. n-ZnO nanorods/p-Si heterojunction showed rectifying I–V characteristics with a turn of voltage of 3.4 V. © 2017 Elsevier B.V.

Nandita Dasgupta

Department of Electrical Engineering

Mamidanna Sri Ramachandra Rao

Department Of Physics

D. M. Priyadarshini

F. Bellarmine

Argon lasers

Electric fields

Heterojunctions

II-VI semiconductors

nanorods

Nanostructures

photoluminescence

Photoluminescence spectroscopy

Pulsed laser deposition

Pulsed lasers

Scanning electron microscopy

Transmission electron microscopy

Zinc oxide

ALIGNED NANORODS

C axis oriented

Flat surfaces

GAS AMBIENTS

NANORODS GROWN

Pulsed-laser deposition technique

Zinc interstitials

ZnO nanostructures

Nitrogen compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Applied Surface Science

We demonstrate reversible p-type nature of pulsed laser deposited (P, N) codoped ZnO thin films using rapid thermal annealing process. As grown thin films exhibited change in conductivity from p to n-type over a span of 120 days. Non-annealed n-type thin films contain unintentional donor impurities such as hydrogen and carbon. X-ray photoelectron spectroscopy and Raman measurements conclusively show that hydrogen passivates nitrogen acceptors by forming N[sbnd]H complex. Carbon can be annealed out at 600 °C, whereas, the dissociation of N[sbnd]H complex takes place at 800 °C. The films revert its p-type nature at an annealing temperature of 800 °C. © 2016 Elsevier B.V.

Reversible p-type conductivity in H passivated nitrogen and phosphorous codoped ZnO thin films using rapid thermal annealing

In this study, the effect of annealing ambient on SnO 2 thin film transistors (TFTs) is presented. Phase pure SnO 2 films have been deposited using solution processed spin coating technique with SnCl 2 as the precursor material. The films are annealed at 500 °C for 1 h in different annealing ambient conditions with varying N 2 :O 2 ratio. Top gate, bottom contact TFTs have been fabricated with SnO 2 as the channel layer, silicon as the gate, silicon dioxide as the dielectric and gold as the contact material. XRD patterns reveal the amorphous nature of films. AFM image shows that the spin coated films are pin-hole free with extremely smooth surface morphology. PL and XPS measurements reveal that with increase in N 2 % during annealing, the defects in the films increase. However, with increase in nitrogen concentration, the device performance improves, the threshold voltage shifts towards lower values and mobility increases, but very high N 2 % is not suitable for device operation, a 70% N 2  + 30% O 2 annealing ambient is found to be suitable with devices showing saturation mobility of 0.23 cm 2 V −1 s −1 and threshold voltage of 6.8 V and on/off ratio of 10 6 . © 2016 Elsevier B.V.

Effect of annealing ambient on SnO 2 thin film transistors

Enhancing luminescence characteristics is one of the key challenges in ZnO nanostructures for highly efficient UV-blue LEDs and laser diodes. Non-conventional PLD growth parameters have been used to tailor the polar and semi-polar surfaces of ZnO nanostructures on MgO substrates. Despite the similar growth temperature, use of N2 ambient gas allowed the fabrication of well-aligned polar nanostructures; whereas, nanostructures grown with Ar ambient are semi-polar in nature. By means of cathodoluminescence spectroscopy, we demonstrate that the UV emission can be significantly enhanced by 11 times for semi-polar nanostructures. The enhanced luminescence is attributed to reduced polarization electric fields along the c-axis. © 2016 The Royal Society of Chemistry.

Fulltext

RSC Advances

Polarity control and enhanced luminescence characteristics of semi-polar ZnO nanostructures grown on non-polar MgO(100) substrates

Abstract We report on the growth of violet emitting p-type ZnO thin films, with phosphorous (P) and nitrogen (N) codoping, using pulsed laser deposition. XPS studies show that the phosphorous is substituted at Zn site, whereas nitrogen is substituted at oxygen site. Hall measurements confirmed the p-type nature in codoped ZnO thin films. I-V characteristics of the heterojunction formed by n-Si and P, N: ZnO showed rectifying nature. Strong violet emission in PL spectra is attributed to the formation of zinc vacancies. We propose a defect complex, (P Zn -V Zn -4N O ), which acts as an effective acceptor in the P and N codoped ZnO. © 2015 Elsevier B.V.

Zn-vacancy induced violet emission in p-type phosphorus and nitrogen codoped ZnO thin films grown by pulsed laser deposition

Bright yellow and white-yellow light emitting ZnO-V2O5 polycrystalline powders are synthesized by engineering zinc oxide and different zinc vanadate phases. Emission characteristics strongly depend on different zinc vanadate phases. The bright yellow emission is originated from the 3T2 → 1A1 and 3T1 → 1A1 transitions in the VO4 tetrahedra of zinc vanadate phase. White-yellow emission is the combination of blue and green emissions due to native point defects of ZnO and the yellow and red emission from zinc vanadate. © 2015 Acta Materialia Inc.

Scripta Materialia

Tunable optical properties of multiphase ZnO-V2O5 polycrystalline powders

Enhanced photoluminescence and heterojunction characteristics of pulsed laser deposited ZnO nanostructures

Journal	Data powered by TypesetApplied Surface Science
Publisher	Data powered by TypesetElsevier B.V.
ISSN	01694332
Open Access	No