Integrated films of transition metal oxides for information technology

Abstract

The recently developed ability to grow layers of transition metal oxides with atomic precision by means of physical vapor deposition has opened up a possibility of monolithic integration of these oxides on semiconductors. Here we review the recent progress in integrating ferroelectric films with Si and Ge, and their potential applications in electronics and nanophotonics. Perovskite films described in the talk were grown by molecular beam epitaxy (MBE) and, when possible, chemical routes were tested via atomic layer deposition (ALD). Design of the structures and analysis of the experimental results were aided by density functional theory (DFT).

Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

“…Transition metal oxides (TMOs) have attracted great attention in fundamental research field recently, because of their diverse physical properties, materials science, renewable energy, and microelectronics and nanotechnology fields applications [1][2][3][4]. They were used as light-emitting diodes (LEDs) [5], smart windows [6], and electrode material for Liion batteries [7].…”

Surface-hydrogen-induced metallization and rumpling in thin BaTiO3 films

“…4 As BTO is ferroelectric, its integration with Si or Ge adds additional versatility in the construction of a ferroelectric FET, [5][6][7] in microwave device applications, 8 or as a nonlinear optical material for Si nano-photonic devices. 9 Due to this interest in utilizing ferroelectricity of BTO, it is crucial that the polarization of BTO is kept intact during growth and processing, and so the understanding of the effects of defects on the polarization is essential.…”

“…24 OH groups caused by H absorption has also been suggested as a source of resistivity degradation in bulk BTO. 19 The adsorption of atoms and molecules on BTO surfaces is an important topic; perovskites have been shown to be effective catalysts for removing CO and CH 4 , 25 and BTO is a particularly effective catalyst for the combustion of CH 4 . 26 Prior research shows that the adsorption of H 2 O on the TiO 2 -terminated (001)BTO surface leads to disassociation into H + and OH -groups, 27,28 and ~20% of Ti surface atoms have these OH -groups; the OH -adsorbed on Ti is enough to reverse the polarization of the surface TiO 2 layer.…”

High ferroelectric polarization in c-oriented BaTiO3 epitaxial thin films on SrTiO3/Si(001)

“…9,10 Moreover, the growth of epitaxial BTO on Si(001) requires a buffer layer, being used either yttria-stabilized zirconia (YSZ) and/or LaNiO 3 (LNO), [11][12][13][14][15] or SrTiO 3 (STO). [5][6][7][8][16][17][18][19][20][21] The YSZ buffer layer is combined with other layers to accommodate progressively the high lattice mismatch of around 9% with BTO. The high mismatch causes in-plane compressive epitaxial stress, favoring growth of c-oriented BTO with high ferroelectric polarization for a broad range of BTO thickness.…”

“…13 In the case of the STO buffer layer, its lattice parameter is much closer to that of BTO permitting epitaxial growth without additional layers. The functional characterization of BTO film on STO/Si(001) has been usually based on piezoresponse force microscopy measurements, 16,18,19,21 which is known that can not be taken as an unambiguously demonstration of ferroelectricity. [22][23][24] Recently, the hysteretic dependence of the resistance with the writing voltage expected for a ferroelectric tunnel junction was observed for BTO tunnel junctions on La 2/3 Sr 1/3 MnO 3 /STO/Si(001).…”