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In this work, a novel thermoresponsive switching transistor is developed through the rational design of active materials based on the typical field-effect transistor (FET) device configuration, where the active material is composed of a blend of a thermal expansion polymer and a polymeric semiconductor. Herein, polyethylene (PE) is employed as the thermal expansion polymer because of its high volume expansion coefficient near its melting point (90–130 °C), which similarly corresponds to the overheating point that would cause damage or cause fire in the devices. It is revealed that owing to the thermistor property of PE, the FET characteristics of the derived device will be largely decreased at high temperatures (100–120 °C). It is because the high volume expansion of PE at such high temperature (near its Tm) effectively increases the distance of the crystalline domains of poly(3-hexylthiophene-2,5-diyl) to result in a great inhibition of current. Besides, the performance of this device will recover back to its original value after cooling from 120 to 30 °C owing to the volume contraction of PE. The reversible FET characteristics with temperature manifest the good thermal sensitivity of the PE-based device. Our results demonstrate a facile and promising approach for the development of next-generation overheating shutdown switches for electrical circuits.

We report that the quasibound states at the above-barrier region in type-II ZnTe/CdSe superlattices can be clearly observed at room temperature by photoreflectance, contactless electroreflectance, as well as photoconductivity measurements. We provide concrete evidence to confirm that free-carrier confinement at barrier layer ͑either in the valence-band CdSe layer or in the conduction-band ZnTe layer͒ does exist. It is found that the barrier-width dependence of the above-barrier ground-state transition energies can be described well by the constructive interference condition. We also observe the absorptive spatially indirect transition between electrons confined in the CdSe and holes confined in the ZnTe layers.

Articles you may be interested inSurface photovoltage spectroscopy of metamorphic high electron mobility transistor structures Room-temperature photoreflectance and photoluminescence characterization of the AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures with varied quantum well compositional profiles Using room-temperature surface photovoltage spectroscopy ͑SPS͒, we have characterized a GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transistor ͑pHEMT͒ structure. Signals have been observed from every region of the sample. From a line shape fit to the normalized first derivative of the surface photovoltage signal with respect to photon energy, the two-dimensional electron gas density (N s ) was obtained and found to be in good agreement with Hall measurement. The Al composition and the properties of the GaAs/GaAlAs superlattice buffer layer also were obtained from the SPS spectrum. The results demonstrate the considerable potential of SPS for the contactless and nondestructive characterization of pHEMT structures at room temperature.