Volume 87, Issue 2, 15 January 2000
Index of content:
- DEVICE PHYSICS (PACS 85)
87(2000); http://dx.doi.org/10.1063/1.371955View Description Hide Description
A method is described to measure the channel charge density-mobility product in field-effect transistors as a function of lateral channel field. From knowledge of the channel charge density, the channel carrier mobility-lateral field relation is determined. This method was applied to n-channel Si metal–oxide–semiconductor field–effect transistors. The channel charge density was determined at low lateral field as a function of gate-to-channel voltage from capacitancemeasurements and this value was corrected to account for electron saturation velocity effects at higher fields. The electron mobility-field results were obtained for lateral fields up to V/cm, a factor of 5–10 larger than previously obtained, and were fit to the conventional empirical relation for mobility, where is mobility at small lateral fields, is electron saturation velocity, is the magnitude of the lateral channel field, and β is an empirical fitting parameter; a best fit to this relation was obtained for unity β and of cm/s.
87(2000); http://dx.doi.org/10.1063/1.371956View Description Hide Description
acelectrical properties of the heterostructured polymer light-emitting diode consisting of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH–PPV) and sodium sulfonated polystyrene (SSPS) ionomer are studied. It is found that the carrier in SSPS is not the ion but the electron, and the conduction mechanism seems to be a space-charge limited current with exponential trap distribution. Based on the results of the impedance analysis, we propose a microscopic model to explain the enhancement of the electroluminescence efficiency of the indiumtin oxide/MEH–PPV/SSPS/Al structure.
87(2000); http://dx.doi.org/10.1063/1.371957View Description Hide Description
Forcefill is a method used in metallization of ICs to fill via holes with metal. At elevated temperature and under applied pressure the metal flows into the via hole. The method is applicable to aluminum as well as to copper. In this article the mechanism of the process is discussed based on measurements of the kinetics and on finite element calculations of the shear and hydrostatic stress in the film covering the via hole. It is demonstrated that naı̈ve use of deformation maps constructed by Frost and Ashby for the description of the forcefill process easily leads to highly inconsistent results. The calculated stress distribution shows that the relevant shear stress is more than one order of magnitude lower that the applied pressure. Since no deformation map was available for the grain size appropriate for the forcefill experiment a map for 1 μm grains was constructed. This map indicates that for the forcefill process diffusional flow is the dominant deformation mechanism. It is shown that under these conditions the diffusional flow process described by Frost and Ashby is in essence identical to our previously reported stress-induced diffusion model.