Conventional Metal Contact Research Articles

An organic Schottky diode (OSD) based on a-silicon/polycarbazole contact

In this paper a novel organic Schottky diode (OSD) based on polycarbazole is proposed. The article presents fabrication and experimental characterization of an amorphous silicon/polycarbazole organic Schottky diode, particularly with configuration a-Si/p-PCz/ITO, wherein in the said novel Schottky diode amorphous silicon (a-Si) contact has been used in place of conventional metal contact on the semiconducting polymer to form a rectifying contact. The characterization of polymer film was done in terms of morphology, absorbance versus wavelength, bandgap and thickness. I–V measurement was performed by Semiconductor Device Analyzer. The electrical parameters such as barrier height, ideality factor, rectification ratio and reverse saturation current as extracted from I–V characteristics of the device were found to be much better than those reported earlier for Schottky diodes based on polycarbazole. The proposed organic Schottky diode (OSD) exhibits a very low dark current (∼10−14A) and is therefore expected to have great commercial applications.

The contact resistance force relationship of an intrinsically conducting polymer interface

Investigations on contact connector materials for different applications such as in the automotive industry have focused toward the increasing interest of using conducting polymers, as compared to conventional metallic contacts. The aim is to achieve overall improvements in performance as well as cost effectiveness. Currently, extrinsic conducting polymers (ECPs) are employed as conductive coats or adhesives at contact interfaces. However, frictional abrasion within the metal doped polymer (ECP) causes fretting corrosion, which leads to instability in the contact resistance. To overcome this, intrinsically conducting polymers (ICPs) are explored. Hemispherical contact coatings were fabricated using poly(3,4-ethylenedioxythiopene) (PEDOT) or polyaniline/polyvinylchloride (PANI/PVC) commodity blends. Contact resistances were taken using four-wire resistance measurement techniques. The conductivities of in-house fabricated ICP contacts were found to be in the range of 10-2 Smiddotcm-1. The response relating the change of contact resistance under varying compression force appeared to be repeatable with minimum deviation of 2%. The surface profiles of the ICP contacts were also recorded by an optical confocal system. The initial investigation results presented in this paper were used to evaluate and validate the hypothesis of employing ICP contacts to eliminate or minimize wearing and fretting effects

An investigation of the contact behavior of electric distributed filament contacts

The findings of a preliminary experimental investigation into the contact behavior of nonmetallic, distributed filament contacts (DFCs) are reported. The study was designed to probe the effects of numerous fibrous micro-contacts upon the electromechanical behaviors of composite contacts and to compare the resultant behaviors with conventional metal contacts. Four composite materials, representing the variables of interest to this study, were processed into electrical contacts by two novel manufacturing methods. Static and dynamic tests reveal that DFC contact resistances can saturate at a level of as low as 10 g, and that DFC contact stability is, similar to that of metals, dependent upon the contact loads and the contact surface hardness, but nearly independent of the properties of the carbon fibers. The results suggest that it is possible to tailor DFC electro-mechanical characteristics over a range that is not possible with monolithic contact materials by the judicious selection of matrix resin, fiber loading, and surface microstructures.

Current gain in polysilicon emitter transistors

The common-emitter current gain β in a shallow polysilicon emitter transistor is derived by solving the minority-carrier transport equation in the silicon-polysilicon structure. Coupled With the majority-carrier transport, an equation for the current gain is obtained which depends on the physical properties of the polysilicon as well as the silicon emitter and base doping profiles. The calculations are based on the carrier trapping model proposed in the literature and ignore any minority-carrier recombinations. The model predicts the current gain of a polysilicon emitter transistor increases at low current and high temperature and approaches that of a conventional metal contact transistor at high current and low temperature. This is due to the potential barrier across the grain boundaries, while impeding the majority-carrier flow, inject minority carriers as a bias is developed across the grain boundaries. It also predicts a decrease in cutoff frequency f T due to minority carriers stored in the polysilicon.