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Source/drain electrodes contact effect on the stability of bottom-contact pentacene field-effect transistors AIP Advances 2, 022113 (2012) All-metallic lateral spin valves using Co2Fe(Ge0.5Ga0.5) Heusler alloy with a large spin signal Appl. Phys. Lett. 100, 052405 (2012) Contact transport of focused ion beam-deposited Pt to Si nanowires: From measurement to understanding Appl. Phys. Lett. 100, 053503 (2012) Ab initio quantum transport simulation of silicide-silicon contacts J. Appl. Phys. 111, 014305 (2012) Impact of fluorine treatment on Fermi level depinning for metal/germanium Schottky junctions Appl. Phys. Lett. 99, 253504 (2011) Additional information on J. Appl. Phys. A new mechanism of contact resistance formation in ohmic contacts with high dislocation density is proposed. Its specific feature is the appearance of a characteristic region where the contact resistance increases with temperature. According to the mechanism revealed, the current flowing through the metal shunts associated with dislocations is determined by electron diffusion. It is shown that current flows through the semiconductor near-surface regions where electrons accumulate. A feature of the mechanism is the realization of ohmic contact irrespective of the relation between the contact and bulk resistances. The theory is proved for contacts formed to III-V semiconductor materials as well as silicon-based materials. A reasonable agreement between theory and experimental results is obtained.

The temperature dependence of contact resistivity q c in lapped silicon specimens with donor concentrations of 5 Â 10 16 , 3 Â 10 17 , and 8 Â 10 17 cm À3 was studied experimentally. We found that, after decreasing part of the q c (T) curve in the low temperature range, an increasing part is registered with increasing temperature T. It is demonstrated that the formation of contact to a lapped Si wafer results in the generation of high dislocation density in the near-surface region of the semiconductor and also in ohmic contact behavior. In this case, current flows through the metal shunts associated with dislocations. The theory developed is in good agreement with experimental results. V C 2012 American Institute of Physics. [http://dx

We demonstrate that the efficiency droop phenomenon in multiple quantum well InGaN/GaN light-emitting diodes (LEDs) may be connected to the current crowding effect. A numerical model of internal quantum efficiency calculation is presented that takes into account nonuniform lateral carrier injection in the active region. Based on this model, we examine the effect of current crowding on the efficiency droop using comparison of simulated internal quantum efficiency of InGaN LEDs with low and high uniformity of current spreading. The results of simulations and measurements show that the devices with low uniformity of current spreading exhibit higher efficiency droop and lower roll-off current value.

Temperature-dependent internal quantum efficiency (IQE) of multiple quantum well InGaN/GaN light-emitting diodes (LEDs) has been investigated. IQE versus current relation is analysed using the modified rate equation model that takes into account the current crowding effect at different temperatures. The results of calculations are consistent with the fact that droop in IQE at higher currents originates from Auger recombination increased by current crowding. It is shown that unusual experimentally observed temperature dependence of the efficiency droop can be explained by stronger lateral nonuniformity of carrier injection at low temperatures without any assumptions about carrier delocalization from In-rich regions in quantum wells.