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Two-dimensional semiconductors can be used to build next-generation electronic devices with ultrascaled channel lengths. However, semiconductors need to be integrated with high-quality dielectrics—which are challenging to deposit. Here we show that single-crystal strontium titanate—a high-κ perovskite oxide—can be integrated with two-dimensional semiconductors using van der Waals forces. Strontium titanate thin films are grown on a sacrificial layer, lifted off and then transferred onto molybdenum disulfide and tungsten diselenide to make n-type and p-type transistors, respectively. The molybdenum disulfide transistors exhibit an on/off current ratio of 108 at a supply voltage of 1 V and a minimum subthreshold swing of 66 mV dec−1. We also show that the devices can be used to create low-power complementary metal–oxide–semiconductor inverter circuits.

Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4 nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4 can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2 interfaces cause considerable morphological changes in the microorganism's cells and lead to the death of the bacteria.

Since the discovery of two-dimensional electron gas (2DEG) at the oxide interface of LaAlOinterface. The minimal thickness of the polar layer t C that is required for electronic reconstruction is t C =  0  P E/eP, where  P is the dielectric constant of the polar material, E is the energy gap separating the valance band of the polar layer and the conduction band of the nonpolar material, and P is the electric polarization of polar layers [10]. Taking  P = 24, E as STO bandgap of 3.2 eV, and P = 0.526 C m -2 for the LAO/STO (001) interface, t C is calculated to be 4 unit cells (uc) Here we show that this can be accomplished by replacing LAO with LSAT - When grown on STO, the lattice mismatch for LSAT/STO is only 1.0%, which is only one third of the value of LAO/STO (3.0%). Furthermore, STO and LSAT both undergo a similar cubic-to-tetragonal transition below 100 K [25,26], whereby maintaining the structural coherency. Fig. 1(c).Given the nonpolar nature of SrTiO 3 (001), a polar-discontinuity-induced 2DEG is expected at the LSAT/STO (001) interface.The thickness-dependent transport data at 2 K for the LSAT/STO (001), (110), and (111) interfaces are summarized in Figs. 2(a)-2(c), respectively. In Fig. 2(a), the (001) interface becomes conducting when covered by a LSAT layer with thickness t ≥ 5 uc. Furthermore, the low-temperature sheet conductance of LSAT/STO increasers with t, reaching its highest value at t ≈ 12 uc. This conductance improvement is not caused by any increases of carrier density, but it is brought about by a great enhancement of carrier mobility  S , which reaches its peak of 35,000 cm 2 V -1 s -1 at t = 12 uc.And this high carrier mobility is about 30 times larger than that of LAO/STO interfaces prepared under similar conditions [5,21,22]. Also, we note that clear Shubnikov-de Haas conductance oscillations can be observed at 2 K for (001) interfaces with high carrier mobility (Fig. S3 in Supplementary Materials [30]). In addition, the transport data clearly show that there are two critical thicknesses for the LSAT/STO (001) interface: one is at 5 uc where the 2DEG is established and the other is around 12 uc where the mobility is greatest.On the other hand, this high mobility 2DEG is also observed at the annealed (110)-and (111)-orientated LSAT/STO interfaces, which is similar to the LAO/STO interface with different orientations [22,31]. But unlike LSAT/STO (001) interface, both the (110) and (111) (110) and (111) LSAT/STO interfaces show much more robust metallicity. For example, our data show that the high-mobility 2DEG can be maintained in the LSAT/STO (110) and (111) interfaces with a 50-uc-thick LSAT layer, while the LAO/STO (110) and (111) interfaces show low-temperature insulating behavior when LAO thickness is beyond just 10 uc [22].Therefore, two major differences between LSAT/STO and LAO/STO interfaces can be found in Fig. 2. One is the much higher carrier mobility and more robust metallicity at the LSAT/STO interface, and the other one is the observation of two critical th...

Electric field effect in electronic double layer transistor (EDLT) configuration with ionic liquids as the dielectric materials is a powerful means of exploring various properties in different materials. Here, we demonstrate the modulation of electrical transport properties and extremely high mobility of two-dimensional electron gas at LaAlO3/SrTiO3 (LAO/STO) interface through ionic liquid-assisted electric field effect. With a change of the gate voltages, the depletion of charge carrier and the resultant enhancement of electron mobility up to 19 380 cm(2)/(V s) are realized, leading to quantum oscillations of the conductivity at the LAO/STO interface. The present results suggest that high-mobility oxide interfaces, which exhibit quantum phenomena, could be obtained by ionic liquid-assisted field effect.