Field effect

About: Field effect is a research topic. Over the lifetime, 4018 publications have been published within this topic receiving 92613 citations.

A field-effect quantum-well laser with lateral current injection

Abstract: Polarization‐dependent gain switching in a field‐effect quantum‐well laser with lateral current injection is studied. We use the k⋅p method for the optical dipole matrix and take into account the intraband relaxation. Gain switching is achieved by the field effect from a gate terminal in a lateral current injection quantum‐well laser structure. It is shown that the peak gain exhibits a red shift and the peak‐gain amplitude decreases with an increasing electric field for the TE mode. The TM mode is less affected by the external field.

Solid/Gaseous Insulation Systems for Compact HVDC Solutions

Abstract: When energizing an electrical insulation system with a direct voltage the initial field distribution, being a capacitive field distribution free of space charges like under normal ac voltage stress, turns into a stationary resistive field distribution. Both, the stationary field distribution and the duration needed for the transition from the capacitive to the resistive field distribution are governed by the bulk and the surface conductivity of the insulating materials involved. Any change of the field distribution compared to the capacitive field is associated with the accumulation of space charges in the bulk material or surface charges on the interface between different insulating materials. Particularly for gaseous dielectrics a simulation model is presented, which takes into account the generation, recombination and motion of charge carriers. The field calculations using this model are verified by measurements of the surface potential on cylindrical epoxy resin insulators under low electric field stress. By means of the simulation model, the charging of conical insulators under high electric field stress and the influence of field-induced electron emission from the cathode is investigated. The influence of temperature and field strength on the surface and bulk conductivity of epoxy resin material is shown experimentally. The influence of temperature-dependent bulk conductivity on the resistive field distribution is shown using simulations. Current measurements in gas under high field conditions indicate the existence of a source of electric charges besides natural ionization. In order to achieve a faster transition from the initial capacitive field distribution to the stationary resistive field distribution (e.g. when an HVDC system is energized, or when a polarity reversal takes place) and in order to provide a faster decay of surface charge carriers, an increase of the insulators’ surface and bulk conductivity is recommended. For experimental investigations, the surface and bulk conductivity of conventional epoxy resin insulators were adjusted by functional fillers providing a well-defined conductivity of the compound. Aiming for eco-friendly solutions, the electric direct voltage strength of nitrogen, oxygen, and gas mixtures has been determined. Further, the influence of argon in such mixtures has been investigated. With respect to possible application in dc insulation systems the electric strength of three typical electrode arrangements with uniform, slightly and strongly non-uniform electric field has been determined experimentally and relevant values compared to the electric strength in SF6 are given.

Non-ohmic contact resistance and field-effect mobility in nanocrystalline silicon thin film transistors

Abstract: Contact resistance has a significant impact on the electrical characteristics of thin film transistors. It limits their maximum on-current and affects their subsequent behavior with bias. This distorts the extracted device parameters, in particular, the field-effect mobility. This letter presents a method capable of accounting for both the non-ohmic (nonlinear) and ohmic (linear) contact resistance effects solely based upon terminal I-V measurements. Applying our analysis to a nanocrystalline silicon thin film transistor, we demonstrate that contact resistance effects can lead to a twofold underestimation of the field-effect mobility.

Impact of scaling of dielectric thickness on mobility in top-contact pentacene organic thin film transistors

Abstract: The effect of scaling of poly(methylmethacrylate) (PMMA) and cross-linkable poly(4-vinylphenol) (PVP) polymer dielectric thickness on field effect mobility in top contact pentance organic thin film transistors was investigated. Mobility at a constant gate voltage improved significantly with reduction in thickness of both dielectrics. Analysis at a constant gate electric field or identical induced accumulation charge revealed that only a part of the improvement occurs due to simple scaling of dielectric thickness, and the remaining is due to improvement in interface quality. Atomic force microscopic analysis of the dielectric surface revealed that dielectric roughness reduced with reduction in dielectric thickness. A comparison of the two dielectrics also indicates that band mobility is significantly higher in pentacene/PMMA as compared to pentacene/PVP dielectric.