Quantitative interpretation of electron-beam-induced current grain boundary contrast profiles with application to silicon

Abstract

An improved method is described for extracting material parameters from an experimental electron-beam-induced current (EBIC) contrast profile across a vertical grain boundary by directly fitting an analytical expression. This allows the least-squares values of the grain boundary recombination velocity and the diffusion length in each grain to be determined without the need for the reduction of the experimental profile to a few integral parameters, as is required in a previously reported method. Greater accuracy of the extracted values is expected since none of the information contained in the experimental contrast data is discarded and a less extensive spatial range of measured data is required than in the commonly used method. Different models of the carrier generation volume are used in the fitting and the effect of the choice of generation model on extracted values is investigated. In common with other EBIC approaches, this method is insensitive to changes in the diffusion length when the collection efficiency is high and diffusion lengths may not be reliably established in those cases.

Amorphous Silicon / Crystalline Silicon Heterojunction Solar Cells

“…A detailed description of this technique, applied to solar cell materials is given in [183,184]. The term EBIC is used generally to represent a number of techniques based on the measurement of (a) minority, that is, ''injected'' carriers generated by energy deposition by a primary beam or (b) the flow of the primary beam current itself, the latter being less common.…”

Injection in light beam induced current systems: An analytical model

“…In this case, laser intensity should be low enough to avoid saturating minority carriers which allows considering the recombination properties to be independent of injection. A careful evaluation of the maximum of injection becomes as important for such setups as it is for electron beam induced current (EBIC) systems used for these investigations . However, evaluating the amplitude of the injection is not trivial because of the two‐dimensional nature of the generation function in cylindrical coordinates which cannot be approximated as a sphere like assumed for EBIC .…”

Quantitative carrier lifetime measurement with micron resolution

“…Many carrier lifetime measurement techniques have been developed in the last fifteen years. However, on silicon quantitative lifetime information has been extracted from EBIC measurements [19][20][21][22] only for low injection conditions, where the limit is again set by the diffusion length and EBIC is also restricted to samples with contacts and a junction and requires a scanning electron microscope. 2͒ have a very limited spatial resolution of the order of 1 cm, imaging and mapping techniques such as carrier density imaging/ infrared lifetime mapping, [3][4][5] PL imaging ͑PLI͒, 6-9 electroluminescence imaging, 10,11 and microwave detected photoconductance decay 12 reach a spatial resolution of about 50 m. This is limited by the apparatus but also by the diffusion length of the charge carriers.…”