Limiting factors of phosphorus external gettering efficiency in multicrystalline silicon

Abstract

INTERSTITIAL L lExternal gettering by phosphorus diffusion is used to improve the minority carrier diffusion lengths Ln in multicrystalline silicon wafers obtained by different growth techniques.Polix, Silso, Semix and Eurosolare materials were characterized. It is shown that gettering efficiency depends strongly on the origin of the material. For Polix and Eurosolare wafers, the optimal diffusion temperature is around 900°C ; L, increases with diffusion time and tends to saturate, after 8 hours, at about 300 to 500 pm.However the presence of a too large density of defects, or (and) a high concentration of dissolved oxygen atoms (i.e. lo1 ~m -~) limits the external gettering efficiency, probably by an internal gettering of impurities.Competition between external and internal gettering seems to occur.

Silicon-film{sup {trademark}} photovoltaic manufacturing technology. Final technical status report, January 1, 1992--July 31, 1995

“…Initially, the temperature was set .at 875"C, and the time was set at two hours [5]. Various continuous POC13/02 flow mixtures were then investigaied to determine the optimum as determined by maximum improvement in diffusion length.…”

“…The sheet was simply cut in 45 cm lengths instead of 15.5 cm lengths. 5 cm by 45 cm solar cells were fabricated using two different fabrication sequences which were based on the baseline process (Table 6 ) and the advanced process ( Table 7). Table 10 reflects the changes that were made to those processes due to size limitations of the standard "-225 processing equipment: …”

Silicon-film {trademark} photovoltaic manufacturing technology. Annual subcontract report, 1 January 1994--31 December 1994

“…Initially, the temperature was set at 875"C, and the time was set at two hours [2]. Various continuous POC13/02 flow mixtures were then investigated to determine the optimum as determined by maximum improvement in diffusion length.…”

Interaction of Interstitially Dissolved Cobalt and Oxygen-Related Centres in Silicon

“…With increasing oxygen content of the silicon a decrease of the gettering efficiency is observed [1,2]. Since "gettering efficiency" is often characterized by measuring electrical properties (e.g.…”