The high-bias behaviour of the dark forward and reverse current-voltage (I-V ) characteristics of an undoped radio frequency (rf) magnetron sputter deposited boron carbide (p-B 5 C)/p-type crystalline silicon heterojunction has been investigated at different ambient temperatures (130-300 K). The experimental forward current-voltage-temperature (I-V -T ) characteristics indicate that the non-ohmic bulk conduction mechanisms operable in the highly resistive polycrystalline B 5 C counterpart material of this heterojunction largely determine the behaviour of its forward current at high-bias voltages (>0.3 V). The hopping conduction model of Apsley and Hughes for a flat density of localized energy states (Apsley N and Hughes H P 1975 Phil. Mag. 31 1327) can be utilized to elucidate the bias dependence of the measured heterojunction forward current over an extended bias-voltage range (0.4-2.7 V) at temperatures below 260 K. On the other hand, the junction-like conduction processes occurring in the depletion region should limit the high-bias behaviour of the measured heterojunction reverse current. Bardeen's model for a modified Schottky-like barrier at the p-B 5 C/p + -Si interface can be satisfactorily applied to describe the reverse current-voltage characteristics at bias voltages larger than 0.4 V.

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The ac‐impedance of bulk‐like films of pure polyethylene oxide (PEO) polymer was measured as a function of frequency f in the range 0.1 to 107 Hz at various constant temperatures T (155 − 330 K). The as‐measured data were analyzed by electric permittivity and modulus formalisms to unveil which dielectric and conductive relaxation processes were responsible for their relaxation behavior below/above glass transition temperature Tg of pure PEO polymer. At T > Tg, none of the α‐, β‐, or γ‐relaxations could be inferred for studied pure PEO films from frequency variation of measured imaginary part ε′′(f, T) of complex dielectric permittivity trueε~(),fT, as low‐frequency losses masked real dielectric contribution to the measured ε′′(f, T) at low frequencies and high temperatures. However, at T < Tg, a broad, relaxation process has been observed in the high‐frequency part of their isothermal ε′′(f, T) − f spectra, which can be related to the β‐ or γ‐dielectric relaxation process. Nonlinear regressions of the measured ε′′(f, T) − f data for T < Tg yielded moral fits to a simple addition of a Havriliak‐Negami function, and a Bergman‐loss Kohlrausch‐Williams‐Watts‐type function, with the relaxation time τmax(T) obtained from Havriliak‐Negami‐fitting parameters, was found to follow a thermally activated Arrhenius‐like relaxation behavior. Conversely, representation of the imaginary part M′′(f, T > Tg) − f spectra of complex electric modulus trueM~()f=1/trueε~()f was found to depict 2 overlapped relaxation processes, which were detached well by a nonlinear regression of a simple superposition of 2 different M′′(f) expressions having the form of the universal Bergman loss function, where it was found that the relaxation time is also thermally activated.

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