TY - JOUR

T1 - Reverse saturation current density imaging of highly doped regions in silicon

T2 - A photoluminescence approach

AU - Müller, Jens

AU - Bothe, Karsten

AU - Herlufsen, Sandra

AU - Hannebauer, Helge

AU - Ferré, Rafel

AU - Brendel, Rolf

PY - 2012/11

Y1 - 2012/11

N2 - We present a camera-based technique for the local determination of reverse saturation current densities J 0 of highly doped regions in silicon wafers utilizing photoconductance calibrated photoluminescence imaging (PC-PLI). We apply this approach to 12.5×12.5 cm 2 float zone silicon samples with textured surfaces and a homogeneous phosphorous diffusion with sheet resistances between 24 and 230 Ω/□. We find enhanced photoluminescence emission at metallized regions of a sample due to reflection of long-wavelength light at the rear side of the sample. Our measurement setup comprises an optical short pass filter in front of the camera effectively blocking wavelengths above 970 nm and therefore ensuring a correct calibration of the PL signal in terms of excess charge carrier density Δn. We analyze two sets of samples comprising metal contacts to highly doped regions prepared by Laser Transfer Doping (LTD) as well as standard tube furnace phosphorus diffusion. We find a considerably smaller J 0 value of 370 fA/cm 2 for the LTD approach compared to a standard diffusion process resulting in J 0=570 fA/cm 2. On the basis of these results we demonstrate that J 0 imaging is a powerful analysis technique for process optimization.

AB - We present a camera-based technique for the local determination of reverse saturation current densities J 0 of highly doped regions in silicon wafers utilizing photoconductance calibrated photoluminescence imaging (PC-PLI). We apply this approach to 12.5×12.5 cm 2 float zone silicon samples with textured surfaces and a homogeneous phosphorous diffusion with sheet resistances between 24 and 230 Ω/□. We find enhanced photoluminescence emission at metallized regions of a sample due to reflection of long-wavelength light at the rear side of the sample. Our measurement setup comprises an optical short pass filter in front of the camera effectively blocking wavelengths above 970 nm and therefore ensuring a correct calibration of the PL signal in terms of excess charge carrier density Δn. We analyze two sets of samples comprising metal contacts to highly doped regions prepared by Laser Transfer Doping (LTD) as well as standard tube furnace phosphorus diffusion. We find a considerably smaller J 0 value of 370 fA/cm 2 for the LTD approach compared to a standard diffusion process resulting in J 0=570 fA/cm 2. On the basis of these results we demonstrate that J 0 imaging is a powerful analysis technique for process optimization.

KW - Charge carrier lifetime

KW - Diffusion

KW - Photolumincescence

KW - Reverse saturation current density

UR - http://www.scopus.com/inward/record.url?scp=84865497455&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2012.05.026

DO - 10.1016/j.solmat.2012.05.026

M3 - Article

AN - SCOPUS:84865497455

VL - 106

SP - 76

EP - 79

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

ER -