| 摘要 |
<p>Increasing the minority carrier recombination lifetime in a Si body contaminated with a metal of Fe, Cr, Co, Mn, Zn or V, comprises storing the Si body at a temp. to cause the metal to diffuse from the bulk of the Si body to the surface of the body to measurably increase the minority carrier recombination lifetime of the Si body; the storage period is at least 48 hrs. Metal is pref. Fe, and the process pref. comprises the additioanl step of removing diffused Fe from the surface; the Si body is a slice of a single crystal of Si prepd. using the Czochralski technique and having an O content greater than 10 ppma; the Si body is a component of a photovoltaic cell; process causes Fe from regions of the bulk wafer at distances from the wafer surface of less than 10% of wafer thickness to diffuse to the surface. Storage temp. is insufficient to produce O-related defects in the Si but pref. 300-380 deg.C minority carrier recombination lifetime is pref. increased by more than 200 microns secs. Diffused Fe is pref. removed from the surface by polishing storage period for a Si wafer is at least 168 hrs.</p> |
