Preparation and characterization of ZnO thin films on InP by laser-molecular beam epitaxy technique for solar cells

Highly c-axis oriented ZnO thin films were epitaxially grown on semi-insula ting (1 0 0) oriented InP substrates (SI-InP) held at room temperature (RT) , 200 degreesC and 300 degreesC by laser molecular beam epitaxy (L-MBE) i.e ., pulsed laser deposition. Through X-ray diffraction analysis, the materia l, the crystalline quality and the epitaxial lattice matching of the film w ere confirmed. The obtained high intense peak shows that the most preferent ial orientation was (0 0 2),,i.e; along the 'c-axis'. Results obtained from the optical studies indicated that the deposited film showed nearly 95% tr ansparency and acts as anti-reflection medium. Photoluminescence (PL) study confirms the high electrical conductivity of the film and the obtained low -intensity PL spectrum indicates high O/Zn ratio. Further, the elemental pe aks for Zn, O, In and P were identified by EDAX and the spectrum shows the stoichiometry of the ZnO thin films. From the optical absorption spectrum, the optical band gap and the thickness were calculated. The sheet resistanc e of the deposited ZnO thin films was measured for various deposition tempe ratures. Structural, compositional, surface morphological, optical and phot oluminescence characterization results are discussed. (C) 2001 Elsevier Sci ence B.V. All rights reserved.