Monitoring the ammonia gas is of great interest to both environmental benefits and human health. The recent advance in polymer thin film transistors (TFTs) can realize high sensitivity and low-cost gas sensors. Ammonia gas interacts with charge carrier channels and polymer/dielectrics interface through Coulomb force. This is the first report of high sensitivity and reusable ammonia sensor fabricated from thiophene-isoindigo donoracceptor conducting polymer. This kind of polymer has advantages of simple synthesis and excellent air stability. The systematic study is carried out to investigate relationship among chemical structure variation and morphology control of polymer to the performance of ammonia sensor. High crystallinity, favored crystal orientation, and direct percolation routes for analytes are found to be essential to increase the susceptibility of polymers to ammonia gas. By strengthening edge-on morphology, the sensitivity can be enhanced fivefold for the same polymer. The idea can put forward the development of sensor array in a time-efficient manner by employing the morphology effect.

High performance p-type thin-film transistor (p-TFT) was realized by a simple process of reactive sputtering from a tin (Sn) target under oxygen ambient, where remarkably high field-effect mobility (μ FE ) of 7.6 cm 2 /Vs, 140 mV/dec subthreshold slope, and 3 × 10 4 on-current/off-current were measured. In sharp contrast, the SnO formed by direct sputtering from a SnO target showed much degraded μ FE , because of the limited low process temperature of SnO and sputtering damage. From the first principle quantum-mechanical calculation, the high hole μ FE of SnO p-TFT is due to its considerably unique merit of the small effective mass and single hole band without the heavy hole band. The high performance p-TFTs are the enabling technology for future ultra-low-power complementary-logic circuits on display and three-dimensional brain-mimicking integrated circuits.The metal-oxide thin-film transistors (TFTs) 1-22 have attracted much attention for next-generation display due to its high mobility in comparison to the silicon-based TFTs, good optical transparency in visible light region, and compatibility with low-temperature processes. To incorporate control integrated circuit (IC) into display and lower the power consumption, high mobility metal-oxide p-type TFT (p-TFT) is required. Such complementary n-and p-TFTs are the needed technology for tens of years since the TFT invention [17][18][19][20][21][22][23] . However, most metal-oxide TFTs 1-13 show n-type conduction. Only very few oxides such as Cu x O 14,18 , NiO x 15,16 , and SnO 20 exhibit p-type conduction with a low mobility. Therefore, the development of high mobility metal-oxide p-TFT is crucial to embed low-power complementary logic circuits on display for system-on-panel. Previously, we pioneered very high mobility SnO 2 n-TFTs 10-12 . In this paper, we investigated the device performance and material property of SnO p-TFT with the same Sn material. Using hafnium oxide (HfO 2 ) as the gate dielectric, the HfO 2 / SnO p-TFT has a high field-effect mobility (μ FE ) of 7.6 cm 2 /Vs, small 140 mV/dec subthreshold slope (SS), and 3 × 10 4 on-current/off-current (I ON /I OFF ). From the first principle quantum-mechanical calculation, the SnO is one of the best candidates for p-TFT, due to its smaller hole effective mass and unique merit without heavy hole band. The high device performance, simple process, and low-cost material make SnO the excellent candidate for future p-TFTs. ResultsFigure 1(a) and (b) show the transistor's drain-source current versus drain-source voltage (I DS -V DS ), |I DS | versus gate-source voltage (|I DS |-V GS ) and μ FE -V GS characteristics of the HfO 2 /SnO x p-TFTs, where the SnO x was formed by reactive sputter from a Sn target. Good device performance was reached at a low V DS of −1.2 V that is vital to lower the switching power of CV DS 2 f/2, where C and f are the capacitance and operation frequency, respectively. Besides, high hole μ FE of 7.6 cm 2 /Vs, a SS of 140 mV/dec, and an I ON /I OFF of 3 × 10 4 were obtained. The devic...

At an ultrathin 5 nm, we report a new high-mobility tin oxide (SnO2) metal-oxide-semiconductor field-effect transistor (MOSFET) exhibiting extremely high field-effect mobility values of 279 and 255 cm(2)/V-s at 145 and 205 °C, respectively. These values are the highest reported mobility values among all wide-band-gap semiconductors of GaN, SiC, and metal-oxide MOSFETs, and they also exceed those of silicon devices at the aforementioned elevated temperatures. For the first time among existing semiconductor transistors, a new device physical phenomenon of a higher mobility value was measured at 45-205 °C than at 25 °C, which is due to the lower optical phonon scattering by the large SnO2 phonon energy. Moreover, the high on-current/off-current of 4 × 10(6) and the positive threshold voltage of 0.14 V at 25 °C are significantly better than those of a graphene transistor. This wide-band-gap SnO2 MOSFET exhibits high mobility in a 25-205 °C temperature range, a wide operating voltage of 1.5-20 V, and the ability to form on an amorphous substrate, rendering it an ideal candidate for multifunctional low-power integrated circuit (IC), display, and brain-mimicking three-dimensional IC applications.

Bilayers of La0.7Sr0.3MnO3/NiO and LaMnO3/NiO were prepared and magnetic exchange coupling investigated in these bilayers, where the Curie temperature of the ferromagnetic (FM) layer is lower than the Néel temperature of the antiferromagnetic layer. After small-field cooling, the LSMO/NiO bilayer exhibits an exchange bias with field HEB = 60 Oe, whereas the LMO/NiO sample shows weak magnetic interaction (∼22 Oe). The unconventional exchange bias in LSMO/NiO bilayer vanishes as temperature rises above 50 K. The weak magnetic interaction at the LMO/NiO interface is due to a larger Hubbard parameter value and smaller transfer integral value in the Mott insulator LMO compared with that for the FM conductor LSMO. The valence states of Mn and Ni ions across the interfaces for LSMO/NiO and LMO/NiO have been studied using X-ray photoelectron spectroscopy. We speculate that the FM interaction between Ni2+ and Mn4+ gives rise to magnetic regions that pin the ferromagnetic LSMO layer.

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