Trench capacitor and method for producing the same

A method of fabricating a trench capacitor, and a trench capacitor fabricated thereby, are disclosed. The method involves the use of a vacuum impregnation process for a sol-gel film, to facilitate effective deposition of high- permittivity materials within a trench in a semiconductor substrate, to provide a trench capacitor having a high capacitance whilst being efficient in utilisation of semiconductor real estate

Trench capacitor and method for producing the same

A method of fabricating a trench capacitor, and a trench capacitor fabricated thereby, are disclosed. The method involves the use of a vacuum impregnation process for a sol-gel film, to facilitate effective deposition of high-permittivity materials within a trench in a semiconductor substrate, to provide a trench capacitor having a high capacitance whilst being efficient in utilisation of semiconductor real estate

Hole transport in the organic small molecule material α-NPD : evidence for the presence of correlated disorder

In this paper the hole mobility in the amorphous small molecule material N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (a-NPD), which is frequently used in organic light-emitting diodes, is studied. From an analysis of the temperature and layer thickness dependence of the steady-state current density in sandwich-type a-NPD-based hole-only devices, it is found that a conventional mobility model assuming a Poole–Frenkel type field dependence and neglecting the carrier density dependence is not appropriate. Consistent descriptions with equal quality are obtained within the framework of two forms of the Gaussian disorder model (GDM and CDM), within which the presence of energetic disorder is described by a Gaussian density of states and within which spatial correlations between the site energies are absent or are included, respectively. Both models contain a carrier density dependence of the mobility. Based on a comparison of the site densities as obtained from both models with the molecular density, we argue that the analysis provides evidence for the presence of correlated disorder

Electron transport in the organic small-molecule material BAlq - the role of correlated disorder and traps

An analysis is presented of the layer-thickness dependent and temperature-dependent current density in sandwich-type electron-only devices based on the amorphous small-molecule organic semiconductor BAlq, which is frequently used in organic light-emitting diodes. The electron transport can be consistently described by assuming a density of states (DOS) which is a superposition of a Gaussian DOS and an exponential trap DOS, with 85 and 100 meV widths, respectively, using a mobility model which includes the carrier density dependence of the mobility in the Gaussian DOS and assuming either random or spatially correlated site energies. From a comparison of the density of hopping sites obtained from both models and the density of molecules as obtained from chemical analysis, evidence for the presence of correlated disorder is found

Analysis of hole transport in a polyfluorene-based copolymer- evidence for the absence of correlated disorder

The presence of spatial correlation between the disordered transport site energies in semiconducting polymers used in organic electronic devices is known to affect the mobility. However, it is not established whether such a correlation is present in relevant polymers. We study hole transport in a polyfluorene-based copolymer and provide evidence for the absence of spatially correlated disorder in this material, based on an analysis of the current-voltage characteristics of sandwich-type devices. Distinguishing correlated from uncorrelated disorder, which we achieve on the basis of the hopping site density, is shown to be highly relevant for the development of quantitative device models

Hole transport in the organic small molecule material α-NPD : evidence for the presence of correlated disorder

In this paper the hole mobility in the amorphous small molecule material N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (a-NPD), which is frequently used in organic light-emitting diodes, is studied. From an analysis of the temperature and layer thickness dependence of the steady-state current density in sandwich-type a-NPD-based hole-only devices, it is found that a conventional mobility model assuming a Poole–Frenkel type field dependence and neglecting the carrier density dependence is not appropriate. Consistent descriptions with equal quality are obtained within the framework of two forms of the Gaussian disorder model (GDM and CDM), within which the presence of energetic disorder is described by a Gaussian density of states and within which spatial correlations between the site energies are absent or are included, respectively. Both models contain a carrier density dependence of the mobility. Based on a comparison of the site densities as obtained from both models with the molecular density, we argue that the analysis provides evidence for the presence of correlated disorder