Boron Back Surface Field Using Spin-On Dopants by Rapid Thermal Processing

다국어 초록 (Multilingual Abstract)

We have studied the application of a rapid thermal processing (RTP) for boron diusion using
spin-on dopants (SODs). For the diusion, six dierent p-type SODs (four with only boron, one
with boron and aluminium, and one with aluminium and gallium) were used on n-type 1
-cm

oat-zone (FZ) silicon. The sheet resistivity formed with diused boron SODs is suciently low for
use of back surface eld (BSF) in solar cells. A sheet resistivity of under 40
/Sq was obtained by
using rapid thermal diusion (RTD) at 1050 C for 60 s. Also, a sheet resistivity of lower 20
/Sq
was reached at 1100 C for 120 s. A surface concentration of 2 3 1020 cmက3 and a junction
depth of 0.5 0.6 m were measured by electrochemical capacitance voltage (ECV). On the other
hand, the sheet resistivity of BSF diused with an aluminum (Al) and boron mixed SODs was not
absolutely reliable because the measurements of the sheet resistivity were very dicult due to the
crystals of Al that formed on the surface. Using a simple design, we fabricated solar cells with
boron dopants as a BSF. A cell eciency of 14. 6 % on 1
-cm FZ silicon with a Voc of 594 mV
was obtained. We assumed that the losses of eciency and Voc were caused by degradation of the
bulk lifetime of the material after boron diffusion.