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Presents a study that proposed a theory for the junction capacitance of mathematically abrupt diodes. Derivation of a general junction capacitance formula; Information on a capacitance formula for an abrupt junction; Evaluation of the general capacitance formula for symmetrical and asymmetrical abrupt junction.

A model to calculate the current voltage characteristics of organic thin film transistors is presented. The model takes into account the influence of high electric field on trap occupancy. The case of the traps at a single energy level is considered in detail. Relevant equations are solved numerically using an iteration method. The field dependent trap occupancy model is found to change free surface charge Q[sub sf] and drain saturation current I[sub d] significantly. The model is compared with the experimental data published by two different groups. There is good agreement between experimental data and our model. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The space charge limited currents J in conducting organic materials often show J∼V[sup m] (where m > 2) dependence on voltage V. Two models have been used extensively to understand this behavior. In one model, the mobility μ is assumed to be dependent on electric field F. In the other model, an exponential distribution of traps is assumed and the mobility is taken to be independent of field. In this model the influence of the high electric fields present in organic polymers has not been taken into account. We present a model to calculate the J(V) characteristics for single carrier organic polymers taking into account the change in the occupancy of the traps due to the high electrical fields present in these materials. We show that the field dependent trap occupancy (FDTO) model can effectively explain the current-voltage characteristics reported by several different groups. If the FDTO model is used, it is not necessary to use the two different models mentioned above. [ABSTRACT FROM AUTHOR]

We improve the trapping model of carrier transport in conducting polymers by integrating the coupled Poisson and continuity equations numerically. In the case of exponentially distributed traps calculated log J vs 1/T plots are straight lines indicating that the activation of carriers to the extended states can be described by one single activation energy, E[sub eff]. The improved trapping model agrees well with the recent experimental data at high temperatures (i.e., near room temperature). At low temperatures the trapping model does not work since the available thermal energy is not sufficient to ionize the traps. We use the hopping mobility model at low temperatures. The model explains the low-temperature J-V characteristics well. This mechanism of charge carrier transport is similar to that used for interpreting experiments on inorganic amorphous materials. [ABSTRACT FROM AUTHOR]

Focuses on a study which detailed the calculation of the interaction energy of arrays of dislocations with nonperiodic distribution. Reason for conducting the calculations; Focus of studies on strain relaxation in pseudomorphic epilayers; Situation in which the calculated rate of strain relaxation on annealing the metastable layers at higher temperatures is increased.

Presents a study that have grown epitaxial layers of silicon-doped indium-arsenic-antimony by molecular-beam epitaxy on gallium arsenide (GaAs) and GaAs-coated silicon substrates. Absorption coefficient; Use of the fitted value of the Fermi level; Electron concentration.

Focuses on a study which determined the properties of doped and undoped amorphous silicon films deposited by the homogenous chemical vapor deposition (HOMOCVD) technique. Information on HOMOCVD; Methodology of the study; Results and discussion.

Studies band-gap narrowing of gallium arsenide as a function of doping concentration using photoluminescence spectroscopy on samples grown by molecular epitaxy. Technique used in measuring the band gap energy; Details on the experiment; Discussion on the results of the study.

Provides information on a study which examined the infrared response of polycrystalline and epitaxial cobalt silicon[sub2]/silicon Schottky diodes as a function of the silicide thickness. Influence of grain boundary scattering on the silicide; Quantum efficiency of the polycrystalline diodes.

Presents a study that examined the fabrication of conventional and electromagnetically casted multicrystalline silicon solar cells using different passivation schemes. Implementation of plasma-enhanced chemical-vapor-deposition; Information on multicrystalline silicon; Discussion on hydrogen plasma passivation.

Space charge limited currents in organic semiconductors are frequently observed to obey the power law J-V[SUPm] and are attributed to an exponential distribution of traps having two parameters, namely the characteristic distribution energy E[SUBt] and the trap concentration H[SUBt]. We determine these parameters from the J(V) characteristics at two or more temperatures reported in literature. [ABSTRACT FROM AUTHOR]

According to the approximate theory of transport in a conducting organic material containing exponential traps, ln J versus In V plots are straight lines with slope l= T[sub C]/T, where T[sub c] is the characteristic temperature of the trap distribution. It is assumed in this theory that the concentration P[sub t] of trapped holes is much larger than the concentrationp of free holes. Our experiments and recent literature results show that at high applied voltages the observed In d versus In V plots deviate from the straight lines and bend down. The numerical solution presented in this article shows that at high voltages the contribution of p to the space charge does not remain negligible. Calculated In d versus In V plots do bend down consistent with our experimental results. The current approaches the trap-filled limit asymptotically as the applied voltage approaches infinity. [ABSTRACT FROM AUTHOR]

Most conducting organic materials have a background p-type doping varying in the range 10[sup 15]-10[sup 17] cm[sup -3]. We report results of a theoretical and experimental study of carrier transport in p-doped organic Schottky diodes. The theory given in this article shows that in a doped organic material with ohmic contacts the current is ohmic at low voltages. If the ohmic contact at the cathode is replaced by an Al Schottky contact the current varies exponentially with the applied voltage V. The current changes to space charge limited current (SCLC) at high voltages. The voltage at which the change takes place depends on the doping concentrations. In the SCLC regime the current varies according to the well-known V[sup 2] law if there are no traps and the mobility is independent of the electric field. If either trapping or effect of field on mobility is important, the current varies as V[sup m], where m>2. We have investigated experimentally the I-V characteristics of Schottky diodes fabricated using the PPV-based oligomer 2,5-di-n-octyloxy-1,4-bis (4′, 4″-bis-styryl) styrylbenzene (Ooct-OPV5) blended with polystyrene (PS) and the PPV-based polymer poly(2-methoxy-5-(3,7-dimethyloctyloxy)-p-phenylene vinylene) (OC[sub 1]C[sub 10]). As predicted by the theory, Al/Ooct-OPV5:PS/ITO (indium tin oxide) and Al/OC[sub 1]C[sub 10]/ITO Schottky diodes do show that the current varies exponentially with V at low voltages and as SCLC according to the V[sup m] law (with m=3) at high voltages. The V[sup 3] variation of the current in the SCLC regime can be due to trapping or field dependent mobility. It is not possible to distinguish unambiguously between the two mechanisms using the experimental results. The voltage at which transition from the Shockley current to SCLC takes place can be used to determine the background doping concentration. The p-type background doping concentration in the Ooct-OPV5 is found to be ∼10[sup 17] cm[sup -3]. From the tem... [ABSTRACT FROM AUTHOR]