EBIC Investigastion of the Electrical Activity of Dislocations with Different Impurity Atmospheres in Si

Abstract

The dependences of EBIC contrast on beam current and applied bias voltage are investigated for dislocations with different impurity atmosphere. It is shown that the results obtained may be explained taking into account the recombination via point defects in dislocation atmospheres both, for charged and uncharged dislocations. Qualitative models describing the recombination activity of dislocations in Si are proposed.

The Recombination Activity of Dislocations in Deformed Silicon at Low Excitation Levels

“…In this frame the explanation [2] that the contrast behaviour in region 1 is determined by the filling of the level responsible for the barriers fits very well with the present findings and, in addition, with the observation [4] that the decrease of the EBIC contrast with the increase of the beam current starts at higher values of generation rate for dislocations with higher concentration of impurities in their atmosphere. From this point of view the opposite tendencies for the temperature dependence of the EBIC contrast observed in different works even for dislocations of the same type (see, e.g., results summarized in [9]) might be determined by the differences in dislocation impurity atmospheres due to thermal sample treatments.…”

“…The nature of the acceptor states giving rise to the electrostatic barrier is not quite clear up to now, but with a large probability they can be attributed to the dislocation itself, being produced by imperfections in the dislocation core structure generated during the dislocation movement [3]. It was shown later [4] that the recombination properties of dislocations in deformed samples differ from one crystal to another depending on the impurity state of the dislocation atmosphere. This means that the line charge of the dislocations is not the only reason determining their recombination activity, and the spatial distribution of electrically active point defects around the dislocation should be also taken into account.…”

Oxygen Effect on Electrical and Optical Properties of Dislocations in Silicon

“…It was shown [8] that oxygen can be gathered by moving dislocations even at 600 to 700 C and that its concentration in the dislocation atmosphere depends on the oxygen content as well as on the parameters of dislocation motion. The dislocation recombination activity measured by EBIC [9] or LBIC [10] (Electron/Light Beam Induced Current, respectively) was found to depend on the interstitial oxygen content [O i ] of the sample. The majority of the PL investigations have concentrated on characterizing dislocations produced in FZ-Si.…”

Simulation of uncharged dislocation EBIC contrast at high excitation level

“…As shown in [6] using the simple calculations, the logarithmic decay of the EBIC contrast with beam current increasing could be observed for charged dislocations. This model seems to be confirmed for n-Si, in which the logarithmic decrease of dislocation EBIC contrast [4] and evidences for 60º dislocation charging [7] were obtained. Therefore the logarithmic dependence of the EBIC contrast on beam current was considered in many works as an argument supporting the charge of dislocations under study.…”

“…It was shown experimentally [4] that in Si the dependence of dislocation EBIC contrast on beam current had a plateau at a small excitation level and with an increase of excitation level (beginning from some critical value I log ) a smooth decay close to the logarithmic one was observed over a several order change of beam current. The threshold value I log depends on the dopant concentration and sample temperature.…”