Epitaxial La 0.67 (Sr,Ca) 0.33 MnO 3 Films on Si for IR Bolometer Applications
- PDF / 353,039 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 101 Downloads / 233 Views
E3.2.1
Epitaxial La0.67(Sr,Ca)0.33MnO3 Films on Si for IR Bolometer Applications A.M. Grishin, S.I. Khartsev, J.-H. Kim, Jun Lu @ Department of Condensed Matter Physics, Royal Institute of Technology, SE-164 40 Stockholm-Kista, SWEDEN; @ Ångström Microstructure Laboratory, Uppsala University, SE-751 21 Uppsala, SWEDEN ABSTRACT We report on processing and properties of La0.67(Sr,Ca)0.33MnO3 (LSCMO) films grown by pulsed laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/YSZ heteroepitaxial layers. X-ray diffraction shows cube-on-cube growth of epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the “diagonal-onside” manner onto the Bi4Ti3O12 (BTO) template. High resolution TEM images demonstrate sharp interfaces between the buffer layers and LSCMO film as well as rare misfit dislocations on the CeO2/YSZ interface. LSCMO film processing conditions have been optimized to get maximum temperature coefficient of resistivity TCR = 4.4%K-1 and colossal magnetoresistance (CMR) ∆ρ/ρ ∼ 2.9%kOe-1 @ 294K. Almost ultimate CMR performance at room temperature has been achieved due to successive improvement of c-axis orientation of layers: full widths at halfmaximum (FWHM) 0.65, 0.58, 0.65, 1.13 and 0.18 degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. Characterization of electrical noise in CMR film yields noise equivalent temperature difference (NETD) as low as 1.2 µK/√Hz @ 30Hz and 294K. INTRODUCTION Perovskite metal-oxide manganites with the formula La+31-xA+2xMnO3 (A+2 = Ca, Sr, Ba, Pb) attract much attention due to their potential applications for various devices. Such a potential arises from very strong dependence of the resistivity of manganites on magnetic field and temperature (Colossal Magnetoresistance effect, CMR). These occur in close vicinity of semiconductor-to-metal (para-to-ferromagnetic) phase transition temperature Tc. High temperature coefficient of resistivity (TCR), combined with rather low electric excess noise achieved in thin epitaxial films, promise manganites to be the material of choice for uncooled infrared (IR) bolometers. 1 Real progress in industrial environment requires the integration of IR detector array with CMOS readout architecture on the same Si wafer. So far, only few high performance CMR films were grown on the Si. 2-5 In this paper we report on processing and characterization of epitaxial manganite films grown on Si substrates with a Tc tailored to room temperature (RT). To get phase transition at RT we made alloying and fabricated a continuous series of solid solutions La0.67(Sr1-xCax)0.33MnO3. Two ceramics: La0.67Ca0.33MnO3 (LCMO) and La0.67Sr0.33MnO3 (LSMO) were chosen as the ends of La0.67(Sr1-xCax)0.33MnO3 series of alloys.
E3.2.2
To possess high TCR, manganite film should be grown in epitaxial quality. This means a Si substrate should be coated with the buffer layer(s) to meet the following requirements: (i) to minimize film-substrate lattice mismatch, (ii) to match film-substrate thermal expansion coefficients, (iii) to
Data Loading...
