Comparison among lifetime techniques for the detection of transition metal contamination

Surface photovoltage phenomena: theory, experiment, and applications

“…For high (low) values of S b , L is highly underestimated (overestimated) by L app . Unrealistically large and small apparent diffusion lengths correlated with low and high S b , respectively, have indeed been observed by several groups [429,513,547,548]. The demarcation line between the two phenomena lies at S b DaL, for which L app L, regardless of sample thickness.…”

“…It is therefore clear that even if there is no direct excitation of the back part of the sample (i.e., condition (5.7c), 1a ( l, is maintained), the sample cannot be treated as semi-in®nite and the effects of the back surface must be taken into account. While Goodman plots made when condition (5.7c) is not valid frequently remain highly linear, it is clear that use of the simple equations (2.61) or (5.3) should yield an erroneous value of L. Indeed, comparisons between SPV and PCD [445,547], mPCD [429,430], or electrolytic metal tracing (ELYMAT) [430,548] measurements on Si indicated a very good agreement for large sample thicknesses and a poor one for sample thicknesses approaching the diffusion length. In recent years, this has become a more and more pressing problem, especially in industrially-oriented monitoring of Si wafers, due to the improvement in Si wafer quality.…”

Physical understanding and technological control of carrier lifetimes in semiconductor materials and devices: A critique of conceptual development, state of the art and applications

“…The material properties of the silicon used for the device fabrication are decisive for their performance [140][141][142][143][144][145][146][147][148][149][150][151][152][153]. Therefore in research or on an assembly line, it is obligatory to assess the quality of wafers prior to fabrication into devices.…”

“…The maps thus drawn often reveal images of contamination sources. The best acknowledged examples of this kind are the surface photovoltage (SPV) method, measuring the variation of surface potential upon illumination, the detection of photoconductivity decay by microwave reflection (m-PCD), and measurements of the photocurrent collected by a silicon-electrolyte contact (Elymat) [151,152].…”

“…Hence, their proper cognizance together with proper accounting of their effects is essential for a correct explanation of lifetime data. Polignano et al [151,152] made a systematic comparative study of the most common wafer-level techniques for lifetime measurements. These techniques are surface photovoltage, Elymat and microwave-detected photoconductive decay.…”