Regulation of depletion layer width in Pb(Zr,Ti)O₃/Nb:SrTiO₃ heterostructures

Abstract

Improving the tunability of depletion layer width (DLW) in ferroelectric/semiconductor heterostructures is important for the performance of some devices. In this work, 200-nm-thick Pb(Zr0.4Ti0.6)O3 (PZT) films were deposited on different Nb-doped SrTiO3 (NSTO) substrates, and the tunability of DLW at PZT/NSTO interfaces were studied. Our results showed that the maximum tunability of the DLW was achieved at the NSTO substrate with 0.5 wt% Nb. On the basis of the modified capacitance model and the ferroelectric semiconductor theory, we suggest that the tunability of the DLW in PZT/NSTO heterostructures can be attributed to a delicate balance of the depletion layer charge and the ferroelectric polarization charge. Therefore, the performance of some devices related to the tunability of DLW in ferroelectric/semiconductor heterostructures can be improved by modulating the doping concentration in semiconducting electrode materials.

Temperature- and doping-dependent nanoscale Schottky barrier height at the Au/Nb:SrTiO3 interface

“…This study adds insight to the current understanding of metal/NSTO contacts, including all-oxide heterostructures. 17,21 BEEM investigation confirms the MIS model as a valuable platform, where the T-dependence of the SBH arises from the subtle interplay of interfacial quality (interfacial layer capacitance) and NSTO polarizability. The latter is however critically affected by doping, implying that x Nb control across the 0.05-0.5 wt.…”

“…2,11,13,15 Experiments aimed to better characterize and understand such a complex scenario are crucial for fundamental reasons, and appear of practical relevance for the remarkable role played by metal/NSTO interfaces in several proof-of-concept devices and applications (e.g., ferroelectric RAMs, FETs, photodiodes, resistive switches, spin injecting contacts, and gas sensors). 1,2,[16][17][18][19][20][21] In this respect, methods to determine interfacial conduction and band bending in a spatially resolved way and as a function of the relevant controllable parameters (e.g., doping, stoichiometry, temperature, and environment), offer new opportunities to identify and control the underlying physical mechanisms. 3,22 Hereafter, we use Ballistic Electron Emission Microscopy (BEEM) to investigate prototypical Au/NSTO Schottky junctions.…”

Resistive Switching Behavior in Ferroelectric Heterostructures

“…In this situation, the volume resistance becomes more crucial than the interfacial effect. In fact, the optimal thickness of the ferroelectric layer is determined by the width of the initial depletion layer, which is related to the carrier concentration of the ferroelectric layer and the semiconductor electrode, regardless of the ferroelectric polarization . These conclusions have important guiding significance for balancing ferroelectric and conductive properties of ferroelectric heterostructures and further improving RS performance by simple methods.…”

Energy storage and thermodynamics of PNZST thick films with coexisting antiferroelectric and ferroelectric phases

“…Nevertheless, oxygen vacancies accumulate easily at the interface of Pt electrodes, deteriorating the polarization and fatigue resistance of PZ‐based films 18,19 . On the other hand, perovskite oxide electrodes, such as SrRuO 3 (SRO), Nb‐doped SrTiO 3 (NSTO), and LaNiO 3 (LNO), have acceptable electric resistivity and small lattice mismatch with PZ‐based films 10,20‐23 . The oxygen in oxide electrodes can compensate for the oxygen vacancies and improve the polarization fatigue of PZ‐based films 24,25 .…”

“…oxide electrodes, such as SrRuO 3 (SRO), Nb-doped SrTiO 3 (NSTO), and LaNiO 3 (LNO), have acceptable electric resistivity and small lattice mismatch with PZ-based films. 10,[20][21][22][23] The oxygen in oxide electrodes can compensate for the oxygen vacancies and improve the polarization fatigue of PZ-based films. 24,25 However, the effects of different bottom electrodes on the energy storage properties of PZ-based AFE films have not been well understood.…”