Multifunctional heterostructures integrated on Si (100)

Abstract

This paper focuses on the growth of several important oxide systems, including BiFeO 3 (BFO), La 0·7 Sr 0·3 MnO 3 (LSMO), BaTiO 3 (BTO), and non-oxide films including permalloy/MgO and Ni/MgO. It is shown that one can achieve thin-film epitaxy over an extended misfit scale by using the paradigm of DME. This will be critical for the future integration of multifunctional heterostructures onto CMOS-based chips in order to create smart structures for the next-generation solid-state devices. In addition, this paper explores the utility of using laser processing to introduce defect populations that induce magnetism in non-magnetic oxides such as STO and BTO as an alternative to incorporating more traditional magnetic layers into the structure. IntroductionThe integration of complex oxide films and heterostructures within existing electronics can significantly expand the range of functional properties available for device exploitation, including colossal magneto-resistance, magnetocaloric effects, coupled magnetic and polarisation (multiferroic) behaviour, and some interesting physical phenomena including spin, charge and orbital ordering. As a result, there has been a tremendous increase in research related to the deposition of multifunctional thin-film heterostructures for solid-state device technology.1-3 The realization of these expected capabilities requires the integration of various multifunctional materials on substrates of industrial interest, particularly integration with existing silicon (Si)-integrated circuits where total misfit strain can range from 1% up to as much as 25%.4,5 Thus, strain and defect control in these films are essential. The total strain that develops in multilayer thin-film heterostructures has three primary components: (a) lattice misfit arising from the differences in lattice constants between the film and the substrate, (b) thermal misfit arising from differences in coefficients of thermal expansion and (c) microstructural strains arising from defects and alloying elements (dopants). By far the largest of these components is the misfit strain. This paper primarily addresses minimization of the lattice misfit component of the strain.According to conventional wisdom, as outlined under the latticematching epitaxy (LME) paradigm, thin films grow as epitaxial Multifunctional heterostructures integrated on Si (100) Singamaneni, Prater and Narayan ICE Publishing: All rights reserved

Enhanced Coercivity in BiFeO3/SrRuO3 heterostructures

“…In this study, the thickness of BFO layer is held constant at 100nm and SRO layer thickness is varied from 180-23nm; all other parameters were kept constant. As reported in our earlier work [10][11][12], the piezo force microscopic (PFM) switching spectroscopy measurements confirm the room temperature ferroelectric nature of BFO layer. I-V curves showed non-leaky diode-like resistive switching characteristics.…”

Memristive behavior in BaTiO3/La0.7Sr0.3MnO3 heterostructures integrated with semiconductors

“…1, we present the θ-2θ XRD pattern of the BTO/LSMO/MgO/TiN/Si (100) heterostructure. Polarization hysteresis measurements together with Raman spectroscopy and temperature-dependent x-ray diffraction confirm the room temperature ferroelectric nature of BaTiO 3 [7][8][9]. From the θ-2θ XRD data for the (002) peak, we determined the out-of-plane (OOP) lattice parameter of BTO layer is 3.993A o , less than the bulk value of 4.036 A o , indicating that these BTO layers are under compression in OOP, and under tension in the plane of the film.…”

“…RRAM is based on the phenomenon that the reversible switching between a high-resistance state (HRS) and a low-resistance state (LRS) can be controlled by applying a voltage. We have achieved the integration of epitaxial BTO/LSMO heterostructures on Si (100) substrates using MgO/TiN buffer layers by pulsed laser deposition as reported in our previous works [7][8][9], and demonstrated resistive switching in ferroelectric epitaxial BTO layer deposited on silicon substrates, which is the prime focus of this work. Of these, the recent focus has been on the ferroelectric RRAM (FRRAM), where the resistive switching depends on the direction of ferroelectric polarization [4][5][6].…”