1,721,026 research outputs found
Degradation effects at aluminum-silicon schottky diodes
No full textTransport properties of semitransparent Al-Si Schottky barriers employed in electrical investigations of interface states are the subject of this article. These barriers show room temperature aging effects, which we demonstrate to be ascribed to the interaction between the conductive paste used on the metal layer for wire bonding and the Al layer. © 1998 The Electrochemical Society. All rights reserved
Determination of minority-carrier diffusion length by integral properties of electron-beam-induced current profiles
No full textThe diffusion length of minority carriers in n-type floating-zone Si samples is obtained with the electron-beam-induced current technique in planar configuration. The charge collection current data as a function of the beam-junction distance are analyzed on the basis of the]] moment method" developed by Donolato [C. Donolato, Solid-State Electron. 28, 1143 (1985)], which is based on the calculation of the variance of the derivative of the current profile. With respect to other methods reported in literature, this has the advantage that it requires no assumptions on the surface recombination velocity and thus provides a diffusion length value free from its influence. The data are also analyzed with the asymptotic method, which requires conventional assumptions on the surface recombination velocity. The comparison between the results has allowed us to test the capabilities of the above-mentioned method. Particular attention is paid to the injection level and its influence on bulk and surface properties
Determination of bulk and surface transport properties by photocurrent spectral measurements
No full textReliable minority carrier diffusion length and surface recombination velocity values have been obtained from stationary photocurrent measurements. A modified surface photovoltage method has been used to determine diffusion lengths longer than the wafer thickness in high-purity Si, whereas the spectral variation of the photocurrent has been employed to measure the surface recombination velocity. The novelty presented in this paper is that a Schottky diode has been employed in both the methods to collect generated charged carriers. Moreover the same Schottky diode has been employed in both the methods in order to avoid any a priori assumptions on the material transport parameters. This combined application of the two methods at the same device enables the determination of highly reliable results
Processing effects on the electrical properties of defects in silicon
No full textMinority carrier lifetime and Hall effect measurements, as well as capacitance transient spectroscopy, have been used to characterize the defects induced by thermal and stress treatments in float zone n-type silicon. The minority carrier lifetime was analysed with respect to the processing conditions by charge collection scanning electron microscopy. Parameters related to the role of the introduced defects were evaluated from the lifetime values by a fitting procedure based on the Shockley-Read-Hall theory; namely, the energy level, capture cross-section, trap density and dislocation occupation factor were obtained. The same parameters were also deduced from deep level transient spectroscopy (DLTS) and Hall effect measurements. In comparing the results, it was taken into account that by the lifetime analysis only the energy level related to the most efficient minority carrier capture centre could be found, while from DLTS and Hall effect measurements several deep levels were detected. A hypothesis is advanced on the nature of the defects and significant differences, according to the specimen history, are pointed out. © 1989
Junction spectroscopy of highly doped GaAs: detection of the EL2 trap
No full text© 1994 Published by Elsevier B.V.
International Workshop on Expert Evaluation and Control of Compound Semiconductor Materials and Technologies (EXMATEC 94) (2. 1994. Parma, Italia)The disappearance of the electron trap at E_t=E_c-0.82 eV (EL2) level in highly doped samples, observed in the literature for N_D-N_A>1x10^17 cm^(-3) has been assessed by junction spectroscopy investigations of liquid-encapsulated Czochralski GaAs:Te with N_D-N_A up to about 7x10^17 cm^(-3). By choosing appropriate spectroscopy methods, we have detected the EL2 peak, even in the most doped sample. This shows that such a defect is present in the material, but its detection is controlled by the quasi-Fermi level position in the gap, which also affects the Schottky diode operating conditions.Depto. de Física de MaterialesFac. de Ciencias FísicasTRUEpu
Electrical characterization of as-grown and thermally treated 8 inches silicon wafers
No full textMinority and majority carrier properties of as grown and rapid thermally annealed 8′′ Si wafers were investigated. Surface and bulk recombination mechanisms were monitored by measuring surface recombination velocity and minority carrier diffusion length, while the defective state of the material was analyzed by measuring extended defect electrical activity, trap concentration and activation energy. A significant deactivation of the shallow acceptors in the sub-surface region was observed in as-grown wafers and attributed to hydrogen introduced in Si during the chemo-mechanical polishing, while an increase in the defective content of the starting material and, correspondingly, an evident reduction of the diffusion length and an increase in the surface recombination rate were detected in thermally treated wafers
Characterisation of surface and near-surface regions in high-purity Cz Si
No full textBulk, surface, and near surface regions of B doped, Cz grown, Si wafers have been characterised by electrical methods. The starting material was standard, 6′′ and 8′′ Cz Si wafers and high quality wafers with a low concentration of vacancy clusters [1]. The effects of chemical and thermal treatments on the electrical properties of the starting wafers have been investigated
Hydrogen-induced boron passivation in Cz Si
No full textAcceptor deactivation in the near-surface region of as-grown, boron-doped Si wafers was detected by in-depth profiles of the free-carrier density obtained by capacitance-voltage measurements. As this deactivation was only observed in wafers subjected to the standard cleaning procedures used in Si manufacturing, we ascribed it to boron passivation by an impurity introduced during the cleaning process. From the study of the free-carrier reactivation kinetics and of the diffusion behaviour of boron-impurity complexes, we have concluded that the impurity is possibly related to hydrogen introduced during the cleaning treatments. The characteristics of the deep level associated with this impurity have been analysed by deep-level transient spectroscopy
Surface damage in silicon substrates after the SiCl4 dry etch of a poly-Si film
No full textThe damage induced by a SiCl4 dry etching of polySi/Si and polySi/SiO2/Si structures to Si substrate surface was studied by measuring the surface recombination velocity and by relating its changes to the damage data obtained by the usual electrical characterization techniques. Different effects of the damage induced by reactive ion etching on the surface recombination velocity were detected. Lattice damage and contamination induce a light increase of the recombination activity, while changes in the morphology of the surface connected to peculiar etching patterns induce a much stronger increase. © 2001 The Electrochemical Society. All rights reserved
Surface photovoltage analysis of crystalline silicon for photovoltaic applications
No full textSurface photovoltage (SPV) method for the characterization of multicrystalline silicon material for photovoltaic applications has been investigated, in view of its application as in-line characterization tool in photovoltaic industry. Minority carrier diffusion lengths have been measured by SPV on as-grown multicrystalline Si wafers as well as on emitter diffused multicrystalline Si wafers, showing the capability and the flexibility of the method. The usual assumptions for SPV data analyses have been critically discussed. The SPV values of diffusion length have been related with material characteristics and process control. © 2002 Elsevier Science B.V. All rights reserved
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