Effect of bi-layer ratio in ZnO/Al2O3 multilayers on microstructure and functional properties of ZnO nanocrystals embedded in Al2O3 matrix

• Type: Article in International Scientific Journal
• Date: 2014

Authors

Sekhar, KC (Author) Other; Levichev, S (Author) Other; Buljan, M (Author) Other; Bernstorff, S (Author) Other; Koppole Kamakshi (Author) Other; Chahboun, A (Author) Other; Almeida, A (Author) FCUP; Agostinho Moreira, JA (Author) FCUP; Pereira, M (Author) Other; Gomes, MJM (Author) Other

Journal

Title: Applied Physics A: Materials Science and Processing

Vol. 115

Pages: 283-289

ISSN: 0947-8396

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 0 Citations

Scientific classification

FOS: Engineering and technology > Materials engineering

Other information

Authenticus ID: P-008-BFJ

DOI: 10.1007/s00339-013-7809-x

Abstract (EN): Zinc oxide (ZnO) nanocrystals (NCs) embedded in alumina (Al2O3) matrix were produced via rapid thermal annealing (RTA) of pulsed laser deposited ZnO/Al2O3 multilayered nanostructures. The effect of the thickness ratio (R) between Al2O3 and ZnO in one bi-layer on the microstructure and functional properties of NCs has been investigated. Grazing incidence small angle X-ray scattering confirmed the formation of nanocrystals after RTA. Grazing incidence wide angle X-ray scattering studies revealed that ZnO NCs have a high crystalline quality with (100) as preferred orientation. Tensile strain of NCs decreases with increasing R and is correlated to the distribution of NCs. From Raman analysis, it is noticed that the phonon frequency of the E-2 mode, related to the ZnO wurtzite phase, in NCs is shifted towards that of bulk ZnO with increasing R. Photoluminescence studies revealed that the near edge peak position shifts from 382 nm to 371 nm as the ratio R changes from 1.5 to 4 and is attributed to the strain effect. The intensity of emission in the yellow-green region due to defects decreases significantly with increasing R. Current-voltage (I-V) characteristics of Al/ZnO NCs embedded in Al2O3/n-Si (100)/Al have shown a hysteresis behavior. The increasing width of the hysteresis with increasing R revealed that the origin of the hysteresis might be due to the existence of polar surface charges on well-separated NCs. The high-resistance and low-resistance states in I-V hysteresis curves seem to be governed by Fowler-Nordheim tunneling and Schottky emission mechanisms, respectively.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7