Use of low-doped emitters in the characterization of silicon wafers

Abstract

This work has as main objective the qualification of the silicon used as a substrate in the manufacture of solar cells, through the technique of photoconductive decay (technique widely used in the sectors of research and industrial production of this type of devices).

The use of this technique together with the  passivation of surfaces, through the formation of low doped phosphorus emitters (n+pn+ structure), allows the extraction of parameters that will assist the process engineer in the tasks of simulation and theoretical-experimental optimiza-tion of the steps that make up the complete manufacturing process.

The samples, processed in open tube furnaces through the pre-deposition of phosphorus (liquid source of POCl3) followed by oxidation in chlorinated environment (by means of TCA), are characterized with the WCT-100 "Lifetime Tester" equipment, for its effective lifetime (τ_eff - transient and quasi-static modes).

Using the data of the inverse of the lifetime as a function of the concentration of carriers, infor-mation is obtained regarding the volume of the material and the phosphorus emitters formed, thus enabling the analysis of the quality of the material and fundamental stages of the manufacturing process.

DOI:https://doi.org/10.56238/uniknowindevolp-134