SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: P-type semiconductor

171

Cu2O p-type semiconductor hollow porous microspheres have been prepared by using a simple soft-template method at room temperature. The morphology of as-synthesized samples is hollow spherical structures with the diameter ranging from 200 to 500 nm, and the surfaces of the spheres are rough, porous and with lots of channels and folds. The photocatalytic activity of degradation of methyl orange (MO) under visible light irradiation was investigated by UV-visible spectroscopy. The results show that the hollow porous Cu2O particles were uniform in diameters and have an excellent ability in visible light-induced degradation of MO. Meanwhile, the growth mechanism of the prepared Cu2O was also analyzed. We find that sodium dodecyl sulfate acted the role of soft templates in the synthesis process. The hollow porous structure was not only sensitive to the soft template but also to the amount of reagents.

Concepts: Spectroscopy, Light, Electromagnetic radiation, Semiconductor, Visible spectrum, Semiconductors, P-type semiconductor, N-type semiconductor

30

Recently SnSe, a layered chalcogenide material, has attracted a great deal of attention for its excellent p-type thermoelectric property showing a remarkable ZT value of 2.6 at 923 K. For thermoelectric device applications, it is necessary to have n-type materials with comparable ZT value. Here, we report that n-type SnSe single crystals were successfully synthesized by substituting Bi at Sn sites. In addition, it was found that the carrier concentration increases with Bi content, which has a great influence on the thermoelectric properties of n-type SnSe single crystals. Indeed, we achieved the maximum ZT value of 2.2 along b axis at 733 K in the most highly doped n-type SnSe with a carrier density of -2.1 × 10(19) cm(-3) at 773 K.

Concepts: Semiconductor, Materials science, Material, Property, Thermoelectric effect, P-type semiconductor, The Carrier, Carrier Corporation

29

Solar photoelectrosynthesis of methanol was driven on hybrid CuO-Cu(2)O semiconductor nanorod arrays for the first time at potentials ∼800 mV below the thermodynamic threshold value and at Faradaic efficiencies up to ∼95%. The CuO-Cu(2)O nanorod arrays were prepared on Cu substrates by a two-step approach consisting of the initial thermal growth of CuO nanorods followed by controlled electrodeposition of p-type Cu(2)O crystallites on their walls. No homogeneous co-catalysts (such as pyridine, imidazole or metal cyclam complexes) were used contrasting with earlier studies on this topic using p-type semiconductor photocathodes. The roles of the core-shell nanorod electrode geometry and the copper oxide composition were established by varying the time of electrodeposition of the Cu(2)O phase on the CuO nanorod core surface.

Concepts: Oxygen, Carbon dioxide, Copper, Oxide, Semiconductor, Germanium, P-type semiconductor, Copper(II) oxide

27

By bringing an anodically biased needle electrode into contact with n-type Si at its tip in a solution containing hydrofluoric acid, Si is etched at the interface with the needle electrode and a pore is formed. However, in the case of p-type Si, although pores can be formed, Si is likely to be corroded and covered with a microporous Si layer. This is due to injection of holes from the needle electrode into the bulk of p-type Si, which shifts its potential to a level more positive than the potential needed for corrosion and formation of a microporous Si layer. However, by applying square-wave potential pulses to a Pt needle electrode, these undesirable changes are prevented because holes injected into the bulk of Si during the period of anodic potential are annihilated with electrons injected into Si during the period of cathodic potential. Even under such conditions, holes supplied to the place near the Si/metal interface are used for etching p-type Si, leading to formation of a pore at the place where the Pt needle electrode was in contact.

Concepts: Semiconductor, Diode, P-type semiconductor, N-type semiconductor, Hydrofluoric acid

24

Doping-induced solubility control is a patterning technique for semiconducting polymers, which utilizes the reduction in polymer solubility upon p-type doping to provide direct, optical control of film topography and doping level. In situ direct-write patterning and imaging are demonstrated, revealing sub-diffraction-limited topographic features. Photoinduced force microscopy shows that doping level can be optically modulated with similar resolution.

Concepts: Protein, Diffraction, Optics, Topography, Diffraction grating, P-type semiconductor, Angular resolution, Fraunhofer diffraction

6

Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters.

Concepts: Semiconductor, Silicon, Transistor, Bipolar junction transistor, Diode, Electronics, P-n junction, P-type semiconductor

5

Organic electrochemical transistors (OECTs) are receiving significant attention due to their ability to efficiently transduce biological signals. A major limitation of this technology is that only p-type materials have been reported, which precludes the development of complementary circuits, and limits sensor technologies. Here, we report the first ever n-type OECT, with relatively balanced ambipolar charge transport characteristics based on a polymer that supports both hole and electron transport along its backbone when doped through an aqueous electrolyte and in the presence of oxygen. This new semiconducting polymer is designed specifically to facilitate ion transport and promote electrochemical doping. Stability measurements in water show no degradation when tested for 2 h under continuous cycling. This demonstration opens the possibility to develop complementary circuits based on OECTs and to improve the sophistication of bioelectronic devices.

Concepts: Hydrogen, Molecule, Chemistry, Chemical bond, Semiconductor, P-n junction, P-type semiconductor, Extrinsic semiconductor

1

Recent work has demonstrated excellent p-type field-effect switching in exfoliated black phosphorus, but type control has remained elusive. Here, we report unipolar n-type black phosphorus transistors with switching polarity control via contact-metal engineering and flake thickness, combined with oxygen and moisture-free fabrication. With aluminium contacts to black phosphorus, a unipolar to ambipolar transition occurs as flake thickness increases from 3 to 13 nm. The 13-nm aluminium-contacted flake displays graphene-like symmetric hole and electron mobilities up to 950 cm(2) V(-1) s(-1) at 300 K, while a 3 nm flake displays unipolar n-type switching with on/off ratios greater than 10(5) (10(7)) and electron mobility of 275 (630) cm(2) V(-1) s(-1) at 300 K (80 K). For palladium contacts, p-type behaviour dominates in thick flakes, while 2.5-7 nm flakes have symmetric ambipolar transport. These results demonstrate a leap in n-type performance and exemplify the logical switching capabilities of black phosphorus.

Concepts: Oxide, Semiconductor, Demonstration, Phosphorus, Diode, Type, P-type semiconductor

0

Solution-processed n-type organic field-effect transistors (OFETs) are essential elements for developing large-area, low-cost, and all organic logic/complementary circuits. Nonetheless, the development of air-stable n-type organic semiconductors (OSC) lags behind their p-type counterparts. The trapping of electrons at the semiconductor-dielectric interface leads to a lower performance and operational stability. Herein we report printed small molecule n-type OFETs based on a blend with a binder polymer, which enhances the device stability due to the improvement of the semiconductor-dielectric interface quality and a self-encapsulation. Both combined effects prevent the fast oxidation of the OSC. Additionally, a CMOS-like inverter is fabricated depositing a p-type and n-type OSCs simultaneously.

Concepts: Electron, Semiconductor, Transistor, Germanium, Diode, P-n junction, P-type semiconductor, N-type semiconductor

0

The ecofriendly synthesis of organic semiconductors with heterojunctions is of interest and requires surfactants to stabilize colloidal nanoparticles (NPs) in aqueous solution. The use of conventional surfactants results in p-n heterostructured NPs, in which both p- and n-type semiconductors are phase separated and confined within a core surrounded by the surfactant shell. The performances of these devices, however, are not comparable to those of solid organic semiconductor films. Further efforts are required to understand and control the morphological structure of the nanoparticles to improve their performances. Here, by using a new class of polyethyleneglycol-based surfactant, PEG-C60, we synthesized unique p-n heterostructured water-borne NPs that comprise a p-type semiconductor core and an n-type PEG-C60 shell. We demonstrate that the morphology gives rise to charge separation superior to conventional water-borne NPs. These PEG-C60-based water-borne NPs can, thus, provide a new paradigm in the current field of water-based organic semiconductor colloids.

Concepts: Semiconductor, Emulsion, Solution, Diode, Semiconductors, P-n junction, P-type semiconductor, N-type semiconductor