| Description |
5 p. : digital, PDF file |
| Series |
Subcontract report ; NREL/SR-520-44088 |
|
NREL/SR ; 520-44088.
|
| System Details |
Mode of access: Internet from the Census web site. |
| Note |
Title from title screen (viewed on October 1, 2008). |
|
"September 2008." |
| Summary |
Using a deposited Al layer, optical processing at a temperature below the Si-Al eutectic temperature of Teu=577C for a few minutes and followed by T>Teu for a few more minutes are able to getter metallic precipitates out of multicrystalline Si. To accomplish the same, a few tens of hours are needed when using thermal annealing at 700C. Possible mechanisms involved in optical-processing gettering are proposed: vacancy injection, radiation-enhanced solubility, and radiation-enhanced diffusion of vacancies and metal impurity atoms. Using FeSi2 as a model case for which the Si lattice expands concomitantly with the dissolution of precipitates, physical modeling and numerical simulations uncover and test the conditions for the mechanisms to be effective. The mechanisms are effective if the injected Si vacancies due to alloy formation are nearly all retained inside and evenly distributed throughout the Si bulk at the lower temperature, and if the Fe atom migration energy barrier is reduced by ~0.15 eV by radiation at the higher temperature. On the other hand, for gettering a precipitate species for which the Si lattice will shrink concomitantly with the dissolution of precipitates, the vacancy-injection mechanism will not only be ineffective but should also have a detrimental effect. |
| Subject |
Getters -- Research.
|
|
Semiconductors -- Defects.
|
|
Silicon crystals -- Defects.
|
|
Solar cells -- Research.
|
| Added Author |
Li, Na.
|
|
National Renewable Energy Laboratory (U.S.)
|
| Gpo Item No. |
0430-P-05 (online) |
| Sudoc No. |
E 9.18:NREL/SR-520-44088 |
|
