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Atomically thin narrow-bandgap layered PdSe2 has attracted much attention due to its rich and unique electrical properties. For silicon-compatible device integration, direct wafer-scale preparation of high-quality PdSe2 thin film on a silicon substrate is highly desired. Here, we present the low-temperature synthesis of large-area polycrystalline PdSe2 films grown on SiO2/Si substrates by plasma-assisted metal selenization and investigate their charge carrier transport behaviors. Raman analysis, depth-dependent X-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy were used to reveal the selenization process. The results indicate a structural evolution from initial Pd to intermediate PdSe2-x phase and eventually to PdSe2. The field-effect transistors fabricated from these ultrathin PdSe2 films exhibit strong thickness-dependent transport behaviors. For thinner films (4.5 nm), a record high on/off ratio of 104 was obtained. While for thick ones (11 nm), the maximum hole mobility is about 0.93 cm2 V-1 S-1, which is the record high value ever reported for polycrystalline films. These findings suggest that our low-temperature-metal-selenized PdSe2 films have high quality and show great potential for applications in electrical devices.

Due to the ultra-thin nature and moderate carrier mobility, semiconducting two-dimensional (2D) materials have attracted extensive attention for next-generation electronics. However, the gate bias stress instability and hysteresis are always observed in these 2D materials-based transistors that significantly degrade their reliability for practical applications. Herein, the origin of gate bias stress instability and hysteresis for chemical vapor deposited monolayer WS2 transistors are investigated carefully. The transistor performance is found to be strongly affected by the gate bias stress time, sweeping rate and range, and temperature. Based on the systematical study and complementary analysis, charge trapping is determined to be the major contribution for these observed phenomena. Importantly, due to these charge trapping effects, the channel current is observed to decrease with time; hence, a rate equation, considering the charge trapping and time decay effect of current, is proposed and developed to model the phenomena with excellent consistency with experimental data. All these results do not only indicate the validity of the charge trapping model, but also confirm the hysteresis being indeed caused by charge trapping. Evidently, this simple model provides a sufficient explanation for the charge trapping induced gate bias stress instability and hysteresis in monolayer WS2 transistors, which can be also applicable to other kinds of transistors.

Since the discovery of graphene in 2004, it has become a worldwide hot topic due to its fascinating properties. However, the zero band gap and weak light absorption of graphene strictly restrict its applications in optoelectronic devices. In this regard, semiconducting two-dimensional (2D) materials are thought to be promising candidates for next-generation optoelectronic devices. Infrared (IR) light has gained intensive attention due to its vast applications, including night vision, remote sensing, target acquisition, optical communication, etc. Consequently, the generation, modulation, and detection of IR light are crucial for practical applications. Due to the van der Waals interaction between 2D materials and Si, the lattice mismatch of 2D materials and Si can be neglected; consequently, the integration process can be achieved easily. Herein, we review the recent progress of semiconducting 2D materials in IR optoelectronic devices. Firstly, we introduce the background and motivation of the review. Then, the suitable materials for IR applications are presented, followed by a comprehensive review of the applications of 2D materials in light emitting devices, optical modulators, and photodetectors. Finally, the problems encountered and further developments are summarized. We believe that milestone investigations of IR optoelectronics based on 2D materials beyond graphene will emerge soon, which will bring about great industrial revelations in 2D material-based integrated nanodevice commercialization.

In this study, using gadolinium (Gd) as a dopant, Gd-WO3/Ag/Gd-WO3 (WGd–Ag–WGd) transparent conductive films with improved electrochromic (EC) and energy storage performance were fabricated on glass substrates by reactive sputtering. The EC performance and sheet resistance of WGd–Ag–WGd are shown to be sensitive to the concentration of the Gd dopant. The optimized structure for transparent conducting (TC) coating is obtained to be Gd-WO3 (52 nm)/Ag (12 nm)/Gd-WO3 (42 nm) with a luminous transmittance of 82.7% and a sheet resistance of 3.4 Ω sq−1 at a modest Gd doping concentration of 0.29 at%. Such a film (sample size of 1 cm × 3 cm) exhibits luminous transmittance modulation (ΔTlum = 49.6%), high coloration efficiency (71.4 cm2 C−1 at 633 nm), fast switching time (1.6 s for coloring and 3.2 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of ±1.0 V. By combining the film structure characterization and electrochemical analysis, such a decent performance can be attributed to the embedded island structured monoclinic Gd2O3 on the surface of WO3 which enhanced charge capacity and reaction kinetics compared with undoped amorphous WO3 films. Moreover, the WGd–Ag–WGd films showed superior capacitive capability with a maximum specific capacitance of 124.7 F g−1 at 2 A g−1, suggesting their potential application in electrochemical energy storage (ECES) devices.

Due to the efficient photocarrier separation and collection coming from their distinctive band structures, superlattice nanowires (NWs) have great potential as active materials for high-performance optoelectronic devices. In this work, InGaZnO NWs with superlattice structure and controllable stoichiometry are obtained by ambient-pressure chemical vapor deposition. Along the NW axial direction, perfect alternately stacking of InGaO(ZnO)

Because of their fascinating properties, two-dimensional (2D) nanomaterials have attracted a lot of attention for developing next-generation electronics and optoelectronics. However, there is still a lack of cost-effective, highly reproducible, and controllable synthesis methods for developing high-quality semiconducting 2D monolayers with a sufficiently large single-domain size. Here, utilizing a NaOH promoter and W foils as the W source, we have successfully achieved the fabrication of ultralarge single-domain monolayer WS2 films via a modified chemical vapor deposition method. With the proper introduction of a NaOH promoter, the single-domain size of monolayer WS2 can be increased to 550 μm, while the WS2 flakes can be well controlled by simply varying the growth duration and oxygen concentration in the carrier gas. Importantly, when they are fabricated into global backgated transistors, WS2 devices exhibit respectable peak electron mobility up to 1.21 cm2 V-1 s-1, which is comparable to those of many state-of-the-art WS2 transistors. Photodetectors based on these single-domain WS2 monolayers give an impressive photodetection performance with a maximum responsivity of 3.2 mA W-1. All these findings do not only provide a cost-effective platform for the synthesis of high-quality large single-domain 2D nanomaterials, but also facilitate their excellent intrinsic material properties for the next-generation electronic and optoelectronic devices.

Spinel oxides (AB2O4) with unique crystal structures have been widely explored as promising alternative catalysts for efficient oxygen evolution reactions; however, developing novel methods to fabr...

Amorphous indium—gallium—zinc oxide (a-IGZO) materials have been widely explored for various thin-film transistor (TFT) applications; however, their device performance is still restricted by the intrinsic material issues especially due to their non-crystalline nature. In this study, highly crystalline superlattice-structured IGZO nanowires (NWs) with different Ga concentration are successfully fabricated by enhanced ambient-pressure chemical vapor deposition (CVD). The unique superlattice structure together with the optimal Ga concentration (i.e., 31 at.%) are found to effectively modulate the carrier concentration as well as efficiently suppress the oxygen vacancy formation for the superior NW device performance. In specific, the In1.8Ga1.8Zn24O7 NW field-effect transistor exhibit impressive device characteristics with the average electron mobility of ~ 110 cm2·V−1·s−1 and on/off current ratio of ~ 106. Importantly, these NWs can also be integrated into NW parallel arrays for the construction of high-performance TFT devices, in which their performance is comparable to many state-of-the-art IGZO TFTs. All these results can evidently indicate the promising potential of these crystalline superlattice-structured IGZO NWs for the practical utilization in next-generation metal-oxide TFT device technologies.

Recently, due to the excellent and tunable optoelectrical properties, quasi-two-dimensional (quasi-2D) layered perovskites have attracted tremendous attention for next-generation optoelectronic devices. However, fabricating high-quality 2D perovskite films, especially with low trap density, is still a challenge. Here, we successfully incorporate different concentrations of FA and Cs cations (i.e. mixed cations) into the quasi-2D perovskites of (iBA)2(MA)3Pb4I13 (FA = formamidinium; iBA = iso-butylamine; MA = methylamine) to modulate their thin film qualities, improving their subsequently fabricated device performances. When configured into photodetectors on rigid substrates, the optimal mixed cation-incorporated (iBA)2(MA)3Pb4I13 perovskites exhibit impressive photodetection properties, which are comparable or even better than those of other 2D perovskite-based photodetectors previously reported. Once fabricated as a flexible photodetector on polyimide, the quasi-2D perovskite device demonstrates further improved performances, yielding a good responsivity of 400 mA W−1, a high detectivity up to 1.68 × 1012 Jones and fast response speeds (rise and decay time constants of 43 and 22 ms, respectively) under 532 nm illumination. Importantly, the obtained devices possess excellent mechanical flexibility and durability with photocurrent maintaining 82% of the initial value even after 9000 bending cycles. This work can provide valuable design guidelines of 2D perovskites to obtain high-performance flexible photodetectors for next-generation optoelectronics.

Rational design of active and stable bifunctional electrocatalysts for both hydrogen evolution and oxygen evolution reactions is critical for the realization of renewable energy technologies. Although direct growth of active two-dimensional (2D) nanosheets on the current collector is an effective method to improve the exposure of active sites, the inefficient electron transfer and weak electron interaction between 2D nanosheets and current collectors greatly limit their overall electrochemical performance. Herein, a unique sandwich structure of CoMnP/Ni2P/NiFe is successfully designed via introducing a Ni2P interlayer between CoMnP nanosheets and nickel–iron (NiFe) foam to achieve an excellent bifunctional electrocatalyst in alkaline media. The metallic Ni2P interlayer does not only improve the electron transfer from the current collector of NiFe foam to the catalyst of CoMnP, but also enhances the intrinsic activity of each active site via strong electron interaction. Electrochemical studies show that the resulting electrocatalyst exhibits superior electrocatalytic activity, such as giving a low cell voltage of only 1.48 V at 10 mA cm−2 stably for a long time when applied as both the cathode and anode in alkaline solutions. These results evidently indicate the superior electrochemical characteristics of this sandwich structure, which may provide a new insight into the design of electrocatalysts for different utilizations.

Because of the excellent electrical properties, III-V semiconductor nanowires are promising building blocks for next-generation electronics; however, their rich surface states inevitably contribute large amounts of charge traps, leading to gate bias stress instability and hysteresis characteristics in nanowire field-effect transistors (FETs). Here, we investigated thoroughly the gate bias stress and hysteresis effects in InAs nanowire FETs. It is observed that the output current decreases together with the threshold voltage shifting to the positive direction when a positive gate bias stress is applied, and vice versa for the negative gate bias stress. For double-sweep transfer characteristics, the significant hysteresis behavior is observed, depending heavily on the sweeping rate and range. On the basis of complementary investigations of these devices, charge traps are confirmed to be the dominant factor for these instability effects. Importantly, the hysteresis can be simulated well by utilizing a combination of the rate equation for electron density and the empirical model for electron mobility. This provides an accurate evaluation of carrier mobility, which is in distinct contrast to the overestimation of mobility when using the transconductance for calculation. All these findings are important for understanding the charge trap dynamics to further enhance the device performance of nanowire FETs.

Due to the energy crisis, the development of high-performance photoelectrocatalysts is becoming a hot research area in recent years. Among the materials studied, BiFeO3 (BFO) exhibits excellent photoelectrocatalytic performance due to its moderate bandgap and unique band structure. In this paper, both pure BFO and La-doped BFO were synthesized by solgel method. The average size of the BFO nanoparticles was tuned from 65 to 440 nm. For the La-doped BFO, the average size of the nanoparticles was reduced from 95 to 40 nm with the increase in doping level from 0 to 30%. Next, the photoelectrocatalytic performance of the pure BFO nanoparticles were enhanced with the reduction in nanoparticle size, which was possibly caused by increased surface-to-volume ratio. For the increase in doping of La, the corresponding photoelectrocatalytic performance was first enhanced and then degraded. To understand the obtained results, a mechanism was proposed, which can be attributed to the competition between geometric size effects and surface effects. Our findings provided a controlled way to tune the photoelectrocatalytic performance of BFO system, which is crucial for practical applications.

As an important semiconductor nanomaterial, InP nanowires (NWs) grown with a typical vapor–liquid–solid mechanism are still restricted from their low electron mobility for practical applications. Here, nonpolar-oriented defect-free wurtzite InP NWs with electron mobility of as high as 2000 cm2 V–1 s–1 can be successfully synthesized via Pd-catalyzed vapor–solid–solid growth. Specifically, PdIn catalyst particles are involved and found to expose their PdIn{210} planes at the InP nucleation frontier due to their minimal lattice mismatch with nonpolar InP{2110} and {1100} planes. This appropriate lattice registration would then minimize the overall free energy and enable the highly crystalline InP NW growth epitaxially along the nonpolar directions. Because of the minimized crystal defects, the record-high electron mobility of InP NWs (i.e., 2000 cm2 V–1 s–1 at an electron concentration of 1017 cm–3) results, being close to the theoretical limit of their bulk counterparts. Furthermore, once the top-gated d...

Recently, owing to the excellent electrical and optical properties, n-type In2O3 nanowires (NWs) have attracted tremendous attention for application in memory devices, solar cells, and ultra-violet photodetectors. However, the relatively low electron mobility of In2O3 NWs grown by chemical vapor deposition (CVD) has limited their further utilization. In this study, utilizing in-situ Ga alloying, highly crystalline, uniform, and thin In2xGa2−2xO3 NWs with diameters down to 30 nm were successfully prepared via ambient-pressure CVD. Introducing an optimal amount of Ga (10 at.%) into the In2O3 lattice was found to effectively enhance the crystal quality and reduce the number of oxygen vacancies in the NWs. A further increase in the Ga concentration adversely induced the formation of a resistive β-Ga2O3 phase, thereby deteriorating the electrical properties of the NWs. Importantly, when configured into global back-gated NW field-effect transistors, the optimized In1.8Ga0.2O3 NWs exhibit significantly enhanced electron mobility reaching up to 750 cm2·V–1·s–1 as compared with that of the pure In2O3 NW, which can be attributed to the reduction in the number of oxygen vacancies and ionized impurity scattering centers. Highly ordered NW parallel arrayed devices were also fabricated to demonstrate the versatility and potency of these NWs for next-generation, large-scale, and high-performance nanoelectronics, sensors, etc.

Two-dimensional (2D) nanomaterials have recently attracted considerable attention due to their promising applications in next-generation electronics and optoelectronics. In particular, the large-scale synthesis of high-quality 2D materials is an essential requirement for their practical applications. Herein, we demonstrate the wafer-scale synthesis of highly crystalline and homogeneous monolayer WS2 by an enhanced chemical vapor deposition (CVD) approach, in which precise control of the precursor vapor pressure can be effectively achieved in a multi-temperature zone horizontal furnace. In contrast to conventional synthesis methods, the obtained monolayer WS2 has excellent uniformity both in terms of crystallinity and morphology across the entire substrate wafer grown (e.g., 2 inches in diameter), as corroborated by the detailed characterization. When incorporated in typical rigid photodetectors, the monolayer WS2 leads to a respectable photodetection performance, with a responsivity of 0.52 mA/W, a detectivity of 4.9 × 109 Jones, and a fast response speed (< 560 μs). Moreover, once fabricated as flexible photodetectors on polyimide, the monolayer WS2 leads to a responsivity of up to 5 mA/W. Importantly, the photocurrent maintains 89% of its initial value even after 3,000 bending cycles. These results highlight the versatility of the present technique, which allows its applications in larger substrates, as well as the excellent mechanical flexibility and robustness of the CVD-grown, homogenous WS2 monolayers, which can promote the development of advanced flexible optoelectronic devices.

Because of sluggish kinetics of the oxygen evolution reaction (OER), designing low-cost, highly active, and stable electrocatalysts for OER is important for the development of sustainable electrochemical water splitting. Here, {112} high-index facet exposed porous Co3O4 nanosheets with oxygen vacancies on the surface have been successfully synthesized via a simple hydrothermal method followed by NaBH4 reduction. As compared with the pristine and other faceted porous Co3O4 nanosheets (e.g., {110} and {111}), the as-prepared {112} faceted porous nanosheets exhibit a much lower overpotential of 318 mV at a current density of 10 mA cm–2. Importantly, these nanosheets also give excellent electrochemical stability, displaying an insignificant change in the required overpotential at a current density of 10 mA cm–2 even after a 14 h long-term chronoamperometric test. All these superior OER activity and stability could be attributed to their unique hierarchical structures assembled by ultrathin porous nanosheets, ...

The emerging of graphene has stimulated the exploration of two-dimensional (2D) nanomaterials. As a kind of important semiconducting 2D materials, WS2 shows great potentials in electronics, optoelectronics, and photonics, etc.; however, the synthesis of high quality, large area, uniform and epitaxial 2D WS2 monolayer films is still a challenge. Herein, we report the epitaxial growth of WS2 on sapphire with excellent electrical and optoelectronic properties via an enhanced chemical vapor deposition method. With the assistance of Na2WO4 as well as the investigation of related growth mechanism, large single crystal triangular WS2 monolayer flakes with well-defined orientations are achieved. The corresponding single crystal domain size is larger than 1 mm together with the centimeter-scale continuous film realized. Once fabricated into transistors, the monolayers exhibit excellent device properties, such as high mobility and large on/off current ratio. Also, these devices give respectable photoresponse properties when operated in the photoconductive mode. The peak responsivity can reach 4.6 A W−1. All these results demonstrate the high quality of as-synthesized WS2 monolayers, indicating the bright future of this synthesis technology for 2D materials towards practical applications.

Quasi two-dimensional (2D) layered organic–inorganic perovskite materials (e.g., (BA)2(MA)n−1PbnI3n+1; BA = butylamine; MA = methylamine) have recently attracted wide attention because of their superior moisture stability as compared with three-dimensional counterparts. Inevitably, hydrophobic yet insulating long-chained organic cations improve the stability at the cost of hindering charge transport, leading to the unsatisfied performance of subsequently fabricated devices. Here, we reported the synthesis of quasi-2D (iBA)2(MA)n−1PbnI3n+1 perovskites, where the relatively pure-phase (iBA)2PbI4 and (iBA)2MA3Pb4I13 films can be obtained. Because of the shorter-branched chain of iBA as compared with that of its linear equivalent (n-butylamine, BA), the resulting (iBA)2(MA)n−1PbnI3n+1 perovskites exhibit much enhanced photodetection properties without sacrificing their excellent stability. Through hot-casting, the optimized (iBA)2(MA)n−1PbnI3n+1 perovskite films with n = 4 give the significantly improved crys...

Multiwall carbon nanotubes (CNTs) were synthesized by the annealing of carbonaceous solid at a low-temperature (450 °C). The average diameter of the CNTs is about 50 nm. The length of the CNTs ranges from 200 nm to nearly 1 μm. The as-synthesized CNTs are crystallized. Cobalt nanoparticle is capped at the tip of the CNT. The carbonaceous solid, which contains cobalt nanoparticles, was obtained by the sol–gel autocombustion method. The growth of CNTs occurred in the annealing process, while the combustion process only produced carbonaceous solid and cobalt nanoparticles. The cobalt nanoparticles catalyze the decomposition of carbonaceous solid into carbonaceous gas species, and also catalyze the growth of CNTs during the annealing process.

We demonstrate the synthesis of large-area monolayer WS2 films by chemical vapor deposition (CVD) and investigate their photoresponse properties by fabricating n-type field effect transistors (FETs) with Al as the ohmic contact. Our CVD-grown monolayer WS2 shows an electron mobility of 0.91 cm2 V−1 s−1 and an ON/OFF ratio of 106, indicating its comparable electronic properties to the mechanically exfoliated flake sample. In a vacuum, by applying a gate bias (60 V), the responsivity of the monolayer WS2 phototransistor can increase up to 18.8 mA W−1 and a decent sub-second level response time can be maintained. In contrast, in air, it shows a very fast response time of less than 4.5 ms, but at the cost of responsivity reduction to 0.2 μA W−1. Such a distinctive ambient-sensitive photo-detecting performance can be well-explained by the pronounced effect of charge-acceptor-like O2/H2O molecule adsorption/desorption on the photocarrier transport. Our CVD-grown high quality monolayer WS2 may pave the way for developing industrial-scale optoelectronic devices for photo-detecting and chemical sensing applications.

Van der Waals heterostructures built from two-dimensional materials on a conventional semiconductor offer novel electronic and optoelectronic properties for next-generation information devices. Here we report that by simply stacking a vapor-phase-synthesized multilayer n-type WS2 film onto a p-type Si substrate, a high-responsivity Zener photodiode can be achieved. We find that above a small reverse threshold voltage of 0.5 V, the fabricated heterojunction exhibits Zener tunneling behavior which was confirmed by its negative temperature coefficient of the breakdown voltage. The WS2/Si heterojunction working in the Zener breakdown regime shows a stable and linear photoresponse, a broadband photoresponse ranging from 340 to 1100 nm with a maximum photoresponsivity of 5.7 A/W at 660 nm and a fast response speed of 670 μs. Such high performance can be attributed to the ultrathin depletion layer involved in the WS2/Si p-n junction, on which a strong electric field can be created even with a small reverse voltage and thereby enabling an efficient separation of the photogenerated electron-hole pairs.

Functioning both as electrochromic (EC) and transparent-conductive (TC) coatings, WO3/Ag/WO3 (WAW) trilayer film shows promising potential application for ITO-free electrochromic devices. Reports on thermal-evaporated WAW films revealed that these bifunctional WAW films have distinct EC characteristics; however, their poor adhesive property leads to rapid degradation of coloring-bleaching cycling. Here, we show that WAW film with improved EC durability can be prepared by reactive sputtering using metal targets. We find that, by introducing an ultrathin tungsten (W) sacrificial layer before the deposition of external WO3, the oxidation of silver, which leads to film insulation and apparent optical haze, can be effectively avoided. We also find that the luminous transmittance and sheet resistance were sensitive to the thicknesses of tungsten and silver layers. The optimized structure for TC coating was obtained to be WO3 (45 nm)/Ag (10 nm)/W (2 nm)/WO3 (45 nm) with a sheet resistance of 16.3 Ω/□ and a luminous transmittance of 73.7%. Such film exhibits compelling EC performance with decent luminous transmittance modulation ΔTlum of 29.5%, fast switching time (6.6 s for coloring and 15.9 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of ±1.2 V. Thicker external WO3 layer (45/10/2/100 nm) leads to larger modulation with maximum ΔTlum of 46.4%, but at the cost of significantly increasing the sheet resistance. The strategy of introducing ultrathin metal sacrificial layer to avoid silver oxidation could be extended to fabricating other oxide-Ag-oxide transparent electrodes via low-cost reactive sputtering.

Alloyed wurtzite ZnxCd1−xS nanocrystals (NCs) have been synthesised by the newly developed sol–gel autocombustion method for the first time using zinc nitrate, cadmium nitrate and thiourea as starting materials. The structure, composition and morphology of the products were studied by X-ray diffraction and transmission electron microscopy. The composition of the alloyed NCs can be accurately adjusted by tuning the composition of the starting materials. The composition dependent optical properties of the products were investigated by ultraviolet (UV)–visible absorption and photoluminescence (PL) spectroscopies. With increasing Zn composition, a systematic blue shift was observed in both UV–visible absorption and PL spectra, indicating the homogeneous alloyed characteristics of the ZnxCd1−xS NCs and well controlled optical properties by tuning the composition of the starting materials.

ZnS nanocombs were fabricated via a two-step growth method. By annealing Au coated ZnS nanobelts with the help of SnO2/C, comb-like nanostructures would be formed. In the absence of SnO2/C, Au coated ZnS nanobelts would be evaporated completely at the same temperature. As revealed by high resolution transmission microscopy, the growth direction of the ZnS nanobelts was [210] while that of the branches was [001], which epitaxially grew on the (00 ± 1) side surfaces of the ZnS nanobelts. Self-evaporation was used to explain the formation of the ZnS nanocombs. Photoluminescence spectrum reveals that the ZnS nanocombs had two emission bands at 570 and 635 nm.

The synthesis of single crystalline K 6 Ta 10.8 O 30 nanowires by molten salt method was reported for the first time. X-ray diffraction results indicated that the as-prepared products were pure phase K 6 Ta 10.8 O 30 . Scanning electron microscopy and transmission electron microscopy results showed that the products consisted of wire-like nanostructures with 100–300 nm in diameter and several micrometers in length. High resolution electron microscopy and selected area electron diffraction results indicated that the K 6 Ta 10.8 O 30 nanowires were single crystalline with a growth direction of [0 0 1]. The ultraviolet–visible diffuse reflectance measurement showed that the band gap of the nanowires was about 4.1 eV. The effects of reaction temperature, time, and weight ratio of the precursor (mixture of K 2 CO 3 and Ta 2 O 5 ) to KCl salt on the morphology of the products were investigated.

ZnO:Gd films with (1 0 0) preferred orientation were deposited on glass substrates by reactive radio frequency magnetron sputtering with the deposition temperature of 100–500 °C. The (1 0 0) texture of the ZnO:Gd film is enhanced with the increase of deposition temperature. The average transmittance of the ZnO:Gd films in the visible region is over 83% and the film deposited at 500 °C exhibits the highest transmittance (90%). The optical band gap of the ZnO:Gd films increases from 3.213 to 3.227 eV as the deposition temperature increases. The structural defects induced by Gd doping lead to the weak band gap related emission and the strong defects related emissions of the films.

Bi0.9La0.1FeO3 (BLF) and Bi0.9La0.1Fe0.98Zr0.02O3 (BLFZ) ceramics were synthesized by conventional solid state reaction method. X-ray diffraction studies and Rietveld refinements indicated that both of the samples possessed rhombohedrally distorted perovskite structure. The average grain size of BLFZ (~700 nm) was greatly reduced in comparison with BLF (~6 μm). The remanent magnetization of BLFZ was greatly enhanced compared with BLF. The enhancement of remanent magnetization was attributed to the collapse of the spiral spin structure. Both samples showed exchange bias. The possible reason for the appearance of exchange bias was attributed to the inhomogeneity in doping. The measurements of magnetization as a function of temperature indicated that BLF and BLFZ had almost the same magnetic transition temperature (~355 °C).

Alloyed wurtzite Zn 49 Cd 51 S nanocrystals with nearly 15 at% Mn doped have been synthesized by the sol–gel auto-combustion method. At this work, the doping level of Mn in nanoscale sulfide semiconductors is substantially higher than early reports, so far as we know. The max doping level was established indirectly by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy: no impurities were found in the XRD pattern of the product until the doping level was increased to 15 at%; a characteristic Mn 585 nm emission appeared and the defect related emission diminished in the PL spectrum, when Mn was incorporated into the Zn 49 Cd 51 S nanocrystals; and the intensity of Mn 585 nm emission decreased rapidly, when the doping level was increased from 5 at% to 15 at%. Factors that may benefit the Mn doping were discussed.

Recently, due to the possibility of thinning down to the atomic thickness to achieve exotic properties, layered materials have attracted extensive research attention. In particular, PbI2 , a kind of layered material, and its perovskite derivatives, CH3 NH3 PbI3 (i.e., MAPbI3 ), have demonstrated impressive photoresponsivities for efficient photodetection. Herein, the synthesis of large-scale, high-density, and freestanding PbI2 nanosheets is demonstrated by manipulating the microenvironment during physical vapor deposition. In contrast to conventional two-dimensional (2D) growth along the substrate surface, the essence here is the effective nucleation of microplanes with different angles relative to the in-plane direction of underlying rough-surfaced substrates. When configured into photodetectors, the fabricated device exhibits a photoresponsivity of 410 mA W-1 , a detectivity of 3.1 × 1011 Jones, and a fast response with the rise and decay time constants of 86 and 150 ms, respectively, under a wavelength of 405 nm. These PbI2 nanosheets can also be completely converted into MAPbI3 materials via chemical vapor deposition with an improved photoresponsivity up to 40 A W-1 . All these performance parameters are comparable to those of state-of-the-art layered-material-based photodetectors, revealing the technological potency of these freestanding nanosheets for next-generation high-performance optoelectronics.

Correction for ‘Large-area synthesis of monolayer WS2 and its ambient-sensitive photo-detecting performance’ by Changyong Lan et al., Nanoscale, 2015, 7, 5974–5980.

String-like ZnS/SnO nanowire/nanosheet hierarchical nanoheterostructures were synthesized by a two-stage vapor transport and condensation method. X-Ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize and analyze the as-synthesized products. The results indicated that the synthesized products consisted of numerous rectangular single crystalline SnO nanosheets threaded by single crystalline ZnS nanowires. A growth mechanism for the growth of the string-like nanoheterostructures has been proposed. Room temperature photoluminescence properties of the nanostructures were investigated. Both the emissions from ZnS nanowires and SnO nanosheets were observed in the PL spectrum of the string-like nanoheterostructures. These special heterostructures may find applications in nanoelectronic and photonic devices.