We investigated the temperature dependence of the upper critical field [H c2 (T )] of fluorine-free

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Unipolar resistive switching (URS) as well as bipolar resistive switching (BRS) behaviors in a Cu/TaOx/Pt structure were investigated. Upon increasing the compliance current (Ic), the current-voltage characteristics of the Cu/TaOx/Pt structure showed a URS behavior at Ic = 0.1 mA then experienced a non-reversible transition from the URS to a BRS mode at Ic = 10 mA. Through a detailed analysis of the electrical properties in each resistance state of URS and BRS, we revealed that the permanent transition from the URS to the BRS mode was induced by the formation of stronger Cu metal conductive filaments within the TaOx thin film. More interestingly, both URS and BRS modes were governed by the formation and rupture of conductive filaments, whereas the rupture of these filamentary paths in BRS was proposed due to both Joule heating and electric field effects.

The theoretical collector current model for SiGe-based heterojunction bipolar transistors under parallel-perpendicular kinetic energy coupling and anisotropic masses was validated. Verification was performed by comparison to Monte Carlo (MC) calculations and experimental data obtained from previous publications. Collector current against base-emitter voltage obtained by the present model is comparable to that calculated by the MC method. The measured collector currents as a function of base-collector voltage agreed well with the calculated currents for base-emitter voltages ranging from 0.3 to 0.6 V.Introduction: A theoretical model of carrier transport in heterojunction bipolar transistors (HBTs) is required for improving performance and increasing the speed of devices. Generally, theoretical studies of carrier transport in HBTs use energy-transport, hydrodynamic transport, drift-diffusion transport and quantum transport models [1]. On the other hand, recent work has shown theoretically and has been verified experimentally that the gate leakage currents of metal-oxide semiconductor devices with high-K gate dielectrics are affected significantly by gate electron phase velocity when the phase velocity is higher than thermal velocity [2]. The gate electron phase velocity is applicable because the longitudinal and transverse components of electron motion in a heterostructure are coupled under the effective mass approximation [3]. In addition, a wide-gap emitter of an HBT can inject carriers with velocities higher than the thermal velocity into a narrow-gap base using excess kinetic energy due to the band offset at the emitter-base heterojunction [4]. Recently, we derived the motion of an electron with phase velocity in an HBT with anisotropic masses under an applied bias voltage [5]. In this Letter, verification of the model by comparing it to experimental data from previous papers is reported. The results are discussed in detail.