Sol-Gel and Hydrothermal Derived Mn-doped ZnO Films with Optical and Piezoelectric Properties

Maria Zaharescu; Susana Mihaiu; Cristina Maria Vladut; Ecaterina Tenea; Silviu Preda; Calder?n-Moreno; Mihai Anastasescu; Hermine Stroescu; Irina Atkinson; Nicoleta Apostol; Carmen Moldovan; Mariuca Gartner

Maria Zaharescu �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Susana Mihaiu �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Cristina Maria Vladut �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Ecaterina Tenea �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Silviu Preda �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Jos� Mar�a Calder?n-Moreno �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Mihai Anastasescu �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Hermine Stroescu �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Irina Atkinson �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.
Nicoleta Apostol NIMP-National Institute of Materials Physics, 405A Atomi?tilor, 077125 M?gurele � Ilfov, Romania.
Carmen Moldovan IMT-Bucharest, 126A ErouIancu Nicolae, 077190 Voluntari, Romania.
Mariuca Gartner �Ilie Murgulescu� Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania.

Keywords: Sol-gel, hydrothermal, Mn-doped ZnO films, optical properties, piezoelectric properties

Abstract

In this work, Mn-doped ZnO films obtained by sol-gel (SG) and hydrothermal (HT) methods were prepared for possible optical and piezoelectric applications. The amount of Mn dopant was 1, 2 and 5at% and the films were deposited on glass and Si/SiO₂/Ti/Pt substrates. The comparative characterization of the films for their structure, morphology, optical and piezoelectric properties was achieved. SG films exhibit equiaxed nanoparticles, with diameters around 50 nm, while uniform 1D nanorods, sized about 30 nm diameter and 200-300 nm length, were obtained for the films prepared by HT method. XRD diffractograms reveal the presence of zincite phase, with an improvement in crystallinity of the HT films, which present a stronger orientation along (002) plane (c-axis). Spectroscopic ellipsometry shows that the films obtained by SG are much thinner than the ones obtained by HT, and that the refractive index is increasing with the percent of dopant. The maximum transmission is the highest for the undoped ZnO film and decreases with Mn concentration, but remains over 78% in the visible range. The piezoelectric tests have shown for both SG and HT derived films low d₃₃ coefficient. The highest value of d₃₃ is obtained for HT film with 2at% dopant. Based on the obtained results the research directions for the improvement of piezoelectric properties could be outlined.