Nonvolatile Control of the Electronic Properties of In_2–xCr_xO₃ Semiconductor Films by Ferroelectric Polarization Charge

Abstract

A series of Cr-doped In 2−x Cr x O 3 (ICO) semiconductor thin films were epitaxially grown on (111)oriented 0.71Pb(Mg 1/3 Nb 2/3 )O 3 -0.29PbTiO 3 (PMN-0.29PT) single-crystal substrates by the pulsed laser deposition. Upon the application of an electric field to the PMN-0.29PT substrate along the thickness direction, we realized in situ, reversible, and nonvolatile control of the electronic properties and Fermi level of the films, which are manifested by abundant physical phenomena such as the n-type to p-type transformation, metal−semiconductor transition, metal−insulator transition, crossover of the magnetoresistance (MR) from negative to positive, and a large nonvolatile on-and-off ratio of 5.5 × 10 4 % at room temperature. We also strictly disclose that both the sign and the magnitude of MR are determined by the electron carrier density of ICO films, which could modify the s−d exchange interaction and weak localization effect. Our results demonstrate that the ferroelectric gating approach using PMN-PT can be utilized to gain deeper insight into the carrier-density-related electronic properties of In 2 O 3 -based semiconductors and provide a simple and energy efficient way to construct multifunctional devices which can utilize the unique properties of composite materials.

Room-Temperature Quantum Transport Phenomenon in Low-Temperature-Grown Zn1–xMgxO/ZnO Heterostructures

“…In order to confirm this point, we list the reported highest temperature T h at which the WL effect survives (see Figure b). Indeed, T h (see diamonds) roughly exhibits an increase with decreasing carrier concentration in ZnO-based transport systems. ,,− ,− Similarly, in graphene − and In 2 O 3 -based transport systems, ,− the same situations also appear up. The n value of our samples is in the range of 5.0–76.2 × 10 14 cm –2 .…”

“…Consequently, it is understandable that the WL effect as one of typical quantum transport phenomena survives at room temperature (see Figure b). Similarly, the WL effect at relatively high temperatures ( T > 100 K) has been found in ZnO-based transport systems but not discussed in detail. − In contrast, the WL effect only appears up at low temperatures ( T < 100 K) in other oxides such as In 2 O 3 , ,− SnO 2 , ,− and CdO. , In conventional nonoxide materials like AlGaAs/GaAs heterostructures, the WL effect generally appears up at cryogenic temperatures. Therefore, there may be some distinctive characters in ZnO-based systems, which is also why Zn 1– x Mg x O/ZnO heterostructures are studied in this work.…”

Effects of Illumination and Ferroelectric Field on Nanoscale Al:ZnO Films: Implications for Nonvolatile Multistage Storage and Photosensor Devices

“…Figure 1b presents the XPS spectra of the AZO films in the region of O 1s peaks for the four samples prepared at different R O . The two peaks of the oxygen vacancies (O V , 531.6 eV) and oxygen ions 11,40 In addition, two non-overlapping I−V curves were obtained in the positive (P r + ) and negative polarization states (P r − ). And the slope of the P r + is greater than that of the P r − ; i.e., the resistance of the P r + is samller than that of the P r − .…”

“…The carrier density is important to the semiconductor films, which can be adjusted by changing the preparation conditions, such as deposition atmosphere, temperature, and transition metal doping . One of the most practical methods to achieve the modulation of carrier density is to fabricate the semiconductor films on ferroelectric substrates. − Reversible and nonvolatile modulated carrier density of the films can be achieved by the ferroelectric field effect under the electric field.…”

“…The carrier density is important to the semiconductor films, which can be adjusted by changing the preparation conditions, such as deposition atmosphere, temperature, and transition metal doping . One of the most practical methods to achieve the modulation of carrier density is to fabricate the semiconductor films on ferroelectric substrates. − Reversible and nonvolatile modulated carrier density of the films can be achieved by the ferroelectric field effect under the electric field. The (1– x )­PbMg 1/3 Nb 2/3 O 3 – x PbTiO 3 single crystal at the phase boundary (0.29 ≤ x ≤ 0.33) is widely studied, due to the large ferroelectric polarization ( P r ≈ 30–40 μC/cm 2 ) and excellent piezoelectric coefficient ( d 33 ≈ 2000 pC/N). − It should be noted that the remanent polarization of PMN-PT single crystal is about 30–40 μC/cm 2 , with the corresponding surface charge density around (1.9–2.5) × 10 14 charge/cm 2 . , In order to obtain a large modulation of the carrier-density-mediated physical properties by the ferroelectric field effect, the magnitude of the areal carrier density of the film needs to be equal to or smaller than the PMN-PT surface charge density.…”