Using optical-pump terahertz-probe spectroscopy, we study the relaxation dynamics of photoexcited carriers in graphene at different substrate temperatures. We find that at lower temperatures the tail of the relaxation transients measured by the differential probe transmission become slower, extending beyond several hundred picoseconds below 50 K. We interpret the observed relaxation transients ...

Accurately measuring the bulk minority carrier lifetime is one of the greatest challenges in evaluating photoactive materials used in photovoltaic cells. One-photon time-resolved photoluminescence decay measurements are commonly used to measure lifetimes of direct bandgap materials. However, because the incident photons have energies higher than the bandgap of the semiconductor, most carriers a...

BACKGROUND The challenging biological and mechanical environment of posterolateral fusion (PLF) requires a carrier that spans the transverse processes and resists the compressive forces of the posterior musculature. The less traumatic posterolateral approach enabled by minimally invasive surgical techniques has prompted investigations into alternative rhBMP-2 carriers that are injectable, setta...

The bulk lifetimes of minority ,carriers in n-type l :germanium, in both n and p-type silicon and in n-type magnesium germanide have been investigated at room temperature. The sample was illuminated with periodic light ·flashes produced by a spark gap. The transient change in conductance of the sample after illumination gave the lifetime. In germanium and silicon the measured bulk lifetimes had...

2014 The current-voltage (I-V) characteristics of Au/03B1-sexithienyl/Au sandwich structures have been measured. The I-V curves present two regimes : at high voltages, the square law corresponding to the space-charge-limited current (SCLC) is observed ; the linear variation occurring at low voltages is generally attributed to the ohmic current due to bulk free-carriers. A study of the linear cu...

Physical properties of thin films significantly differ from those of bulk materials. Also, these properties are influenced from the technological parameters of the films deposition technique. Therefore, characterization methods for evaluation of thin film properties become of high importance. A novel approach to the well-known "Hot-Probe" method is proposed and applied in our work. The conventi...

Large reductions in thermal conductivity, in comparison to bulk materials, have been observed in materials structured at the nanoscale level. These reductions are attributed to a combination of classical and quantum size effects that manifest themselves when the characteristic length scales in the nanostructured material become comparable to, or shorter than, the mean free path of the heat carr...

We report a transient absorption microscopy study of charge carrier dynamics in bulk MoS 2 crystals at room temperature. Charge carriers are injected by interband absorption of a 555-nm pulse, and probed by measuring differential reflection of a time-delayed and spatially scanned 660-nm pulse. We find an intervalley transfer time of about 0.35 ps, an energy relaxation time of hot carriers on th...

Topological insulators exhibit a bulk energy gap and spin-polarized surface states that lead to unique electronic properties1–9, with potential applications in spintronics and quantum information processing. However, transport measurements have typically been dominated by residual bulk charge carriers originating from crystal defects or environmental doping10–12, and these mask the contribution...

An ultrafast two-dimensional visible/far-IR spectroscopy based on the IR/THz air biased coherent detection method and scanning the excitation frequencies is developed. The method allows the responses in the far-IR region caused by various electronic excitations in molecular or material systems to be observed in real time. Using the technique, the relaxation dynamics of the photo-excited carrier...