Showing papers by "Jürgen H. Werner published in 1985"
TL;DR: Measurements of the energy distribution of interface states at grain boundary areas in fine-grained silicon films reveal exponentially decaying band tails in the two-dimensional density of states within the band gap in agreement with a model of potential fluctuations.
Abstract: We present measurements of the energy distribution of interface states at grain boundary areas in fine-grained silicon films. A dc method as well as ac-admittance spectroscopy reveals exponentially decaying band tails in the two-dimensional density of states within the band gap. The experimental results are in agreement with a model of potential fluctuations. This model explains the extrapolated band-edge values of the density of states as well as the ratio of the slopes of conduction- and valence-band tails.
99 citations
01 Jan 1985
TL;DR: In this article, the authors present methods for the determination of the density of states at grain boundaries in polycrystalline semiconducting films and bicrystals, based on measurements of the electronic transport of majority carriers.
Abstract: This contribution discusses methods for the determination of the density of states at grain boundaries in polycrystalline semiconducting films and bicrystals. All methods are based on measurements of the electronic transport of majority carriers. The doping method reveals the dominance of band tails in the density of states of fine-grained films of Si and GaAs. This is confirmed by photocapacitance measurements at a grain boundary in a Si bicrystal. Ac-measurements on bicrystals are described within the framework of the “trap transistor model”. General solutions of this model are given in graphical form. It allows for the evaluation of the density of states and the capture cross section for majority carriers. Moreover, potential fluctuations at grain boundaries are resolved and a correlation of electronic and structural properties can be carried out. The application of this technique to a grain boundary in a Si bicrystal indicates that the interface charge is caused by secondary dislocations.
28 citations
TL;DR: A new model is presented, based on generation and recombination of charge carriers at interface states and explicitly takes into account inhomogeneities within the boundary plane, which causes deviations from Lorentzian spectra.
Abstract: Electrical noise at silicon grain boundaries deviates significantly from Lorentzian behavior. The noise shows a $\frac{1}{f}$ dependence over a wide frequency range. We present a new model to explain this behavior quantitatively. Our model is based on generation and recombination of charge carriers at interface states and explicitly takes into account inhomogeneities within the boundary plane. Such inhomogeneities generally cause deviations from Lorentzian spectra. The quantitative analysis allows us to characterize these interface states.
24 citations
TL;DR: In this article, the energy distribution of interface states at grain boundaries in fine-grained silicon films is measured by two independent methods, and the analysis reveals deep exponential band tails in the two-dimensional density of states within the band gap.
Abstract: The energy-distribution of interface states at grain boundaries in fine-grained silicon films is measured by two independent methods. The analysis reveals deep exponential band tails in the two-dimensional density of states within the band gap. It is proposed that these tails originate from Anderson localization of free carriers within potential fluctuations along the grain boundary plane. The measurements are in good agreement with this model.
6 citations
TL;DR: In this article, a Trap Transistor Model for the characterization of traps at the interfacial layer of metal/semiconductor contacts is presented. The method is based on measurements of the ac-admittance of Schottky contacts over a wide frequency range.
Abstract: We present a new method for the characterization of traps at the interfacial layer of metal/semiconductor contacts. The method is based on measurements of the ac-admittance of Schottky contacts over a wide frequency range. The frequency dependence is analyzed within a new Trap Transistor Model which explains the ac-behavior as well as the dc-characteristics. In particular we propose that the ac-current across the interface consists of capacitive as well as of conductive parts. We are able to deduce the density of trap states at the majority carrier Fermi level as well as the capture cross section of the traps. The model is applied to Au/GaAs-Schottky contacts. We find a weak energy dependence for the density of interface states as well as for their capture cross section within the energy range of 0.45eV to 0.57eV below the conduction band edge.
3 citations