Multifunctional heterostructures integrated on Si (100)

Abstract

Complex oxide films and heterostructures exhibit a wide range of functional properties, including colossal magneto-resistance, magnetocaloric effects, coupled magnetic and polarisation (multiferroic) behaviour, and some interesting physical phenomena including spin, charge and orbital ordering. However, putting this functionality to work remains a challenge. To date, most of the work reported in the literature has dealt with heterostructures deposited on closely lattice-matched insulating substrates such as DyScO3 (DSO), NdGaO3 (NGO), MgO and SrTiO3 (STO). Unfortunately, these substrates are incompatible with existing complementary metal oxide semiconductor (CMOS)-based technology, where silicon (Si) (100) substrates dominate. This review covers the major advances in the integration of multifunctional (oxide and non-oxide) materials onto Si (100) substrates reported in the recent past by the authors’ group using pulsed laser deposition in conjunction with a novel layer growth approach called ‘domain-matching epitaxy’ (DME). This paper focuses on the growth of several important oxide systems, including BiFeO3 (BFO), La0·7Sr0·3MnO3 (LSMO), BaTiO3 (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.