Journal of Crystal Growth, Vol.312, No.10, 1683-1686, 2010
A study on structural formation and optical property of wide band-gap Be0.2Zn0.8O layers grown by RF magnetron co-sputtering system
Wide band-gap BeZnO layers were grown on Al2O3 (0 0 0 1) substrate using radio-frequency magnetron co-sputtering. The rate of BexZn1-xO crystallized as a hexagonal structure was x=0.2. From the X-ray photoelectron spectroscopy measurement, the O-Zn bonds relating the crystal structure and the Be-O bonds related to the deviation of the stoichiometry in the BeZnO layer were caught at 530.4 and 531.7 eV in the O 1s spectrum, respectively. Thus, the observance on the Be is peak of 113.2 eV associated with the bonding Be-O indicates that the sputtered Be atoms are substituted for the host-lattice site in ZnO. This Be-O bonding shows a relatively low intense and broadening spectrum caused by large fluctuation of Be content in the BeZnO layer. From the photoluminescence and transmittance measurement, the free exciton and the neutral donor-bound exciton (D-0, X) emissions were observed at 3.7692 and 3.7313 eV, respectively, and an average transmittance rate over 95% was achieved in a wide ultraviolet (UV)-visible region. Also, the binding energy for the (D-0, X) emission was extracted to be 37.9 meV. Through the wide band-gap material BeZnO, we may open some possibilities for fabricating a ZnO-based UV light-emitting diode to be utilized as a barrier layer comprised of the ZnO/BeZnO quantum well structure and/or an UV light emitting material itself. (C) 2010 Elsevier B.V. All rights reserved.