Studies on the use of liquid surface passivation for lifetime measurements on good-quality silicon wafers

We evaluated several liquid passivants, viz. solutions of iodine ethanol (IE), quinhydrone methanol (QHM), and potassium cyanide (KCN), for measuring minority-carrier lifetime. Lifetime was measured by the WCT-100 (Sinton Instruments) and WT-2000 (Semilab). Our results show that both IE and QHM passivation are reliable mechanisms. We also find that the KCN solution is moderately passivating on oxidized surfaces, but is only minimally effective on bare Si surfaces. This paper presents details of our studies. In particular, the effect of illumination on IE-passivated surfaces and possible reasons for variations in lifetime measurement are discussed.