1,721,000 research outputs found
Evaluation of diffusion length at different excess carrier concentrations
No full textThe charge collection technique of scanning electron microscopy is widely used to measure the minority carrier diffusion length L in semiconductors. In order to obtain L, the continuity equation for the excess carrier concentration Δp must be solved with suitable boundary conditions. L is supposed to be constant as a function of the excess carrier concentration. This paper investigates the diffusion length in Si and GaAs in low and high injection regimes, where L is independent of the injection conditions. The results obtained are discussed on the basis of the Shockley-Read-Hall recombination model (W. Shockley and W. Read, Phys. Rev., 87 (1952) 835). The evaluation of the injection dose is also discussed. Indeed, this is very different for the semiconductors under investigation, due to their different electronic properties. © 1994
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
Energy levels associated with extended defects in plastically deformed n-type silicon
No full textDeep Level Transient Spectroscopy (DLTS) investigations of plastically deformed, n-type silicon have been performed. DLTS spectra revealed four lines usually found in deformed silicon but they were unusually dominated by a broadened level located at 0.40 eV from the conduction band edge. This trap resulted to be the most localized at the dislocations, while the other traps are probably related to point defects. The measured DLTS line widths have been simulated by the introduction of a broadening parameter δ, whose dependence on the dislocation density has been studied. Some hypotheses on the physical mechanisms responsible for the line broadening have been advanced. A tentative identification of the defects responsible for the deep levels observed has been performed. © Les Éditions de Physique 1997
Thermal behaviour of deep levels at dislocations in n-type silicon
No full textThe thermal behaviour of deformation-induced traps in plastically deformed ntype silicon has been investigated via Deep Level Transient Spectroscopy. Among the four traps usually detected in plastically deformed silicon only two have been found to survive upon annealing: trap A and trap C located at 0.18-0.23 eV and 0.38-0.43 eV from the conduction band edge, respectively. The last one has been related to dislocations. © Les Éditions de Physique 1997
The injection dose effect on the evaluation of bulk and surface parameters in semiconductors
No full textQuantitative electron-beam-induced current measurements on n-type Si have shown injection dose effects both on bulk parameters (diffusion length) and on surface parameters (surface recombination velocity). The experimental findings are discussed on the basis of the Shockley-Read-Hall recombination model. The evaluation of injection dose in the bulk and at the surface of the semiconductor is also discussed. © 1994 Taylor & Francis Group, LLC
Defect states in plastically deformed-type silicon
No full textThe electronic properties of deformed (Formula presented)-type silicon have been investigated via deep-level transient spectroscopy (DLTS). The four deformation-induced levels usually labeled in the literature as (Formula presented) and (Formula presented) have been found. Their analysis as a function of the deformation parameters and the study of their thermal stability have allowed us to conclude that only the (Formula presented) line, located 0.40 eV from the conduction-band edge, can be attributed to dislocations. The characteristics of this line are reported and discussed, taking advantage of the fact that, owing to the deformation conditions employed, it could be clearly resolved and analyzed in the spectra. The DLTS peaks have been simulated by the introduction of a broadening parameter, whose dependence on the dislocation density has been studied. Moreover, the capture kinetic of this line has been analyzed. The broadening of the observed DLTS peaks has been analyzed on the basis of two different physical mechanisms: crystal disorder and inhomogeneities in the Coulomb potential along the dislocation lines. A tentative identification of the defects responsible for the deep levels observed has been given. © 1997 The American Physical Society
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
Evaluation of diffusion length and surface recombination velocity in semiconductor devices by the method of moments
No full textThe diffusion length and surface recombination velocity of the minority carriers are determined from electron beam induced current (EBIC) profiles on a semiconductor containing a barrier perpendicular to the scanned surface. The evaluation of both the parameters has been obtained by the procedure called "of the first moments," due to Donolato [C. Donolato, Appl. Phys. Lett. 43, 120 (1983)], which is based on the calculation of the first moment about the origin of two induced current profiles. This analysis, based on an exact integral property of the EBIC scans, allows evaluation of the diffusion length and the surface recombination without fitting the experimental profiles. In addition, it is easy to handle and can also be readily applied to real devices
- …
