A MATLAB code is developed and used for calculating the effective surface recombination velocity [S.sub.SRH] and [S.sub.amph], according to (3c) and (4b), at the interface of an oxide passivated p-type Si surface having a doping concentration of 1.5 x [10.sup.16]/[cm.sup.3].
Effective Surface Recombination Velocity versus Excess Carrier Concentration.
The correlation energy affects the occupation probability and hence would certainly affect the recombination rate and recombination velocity. In the previous section the correlation energy was assumed to be zero which would logically mean a reduced recombination activity.
Typical results for the effective surface recombination velocity [S.sub.SRH] and [S.sub.amph] versus surface potential are plotted in Figure 5.
The two-peak-behavior and the peak-hump behavior have been previously reported for surface recombination velocity deduced from measurements of the recombination current at the Si/Si[O.sub.2] interface in gated diodes and gated transistors (e.g.
On the other hand, the present analysis firmly attributes the two-peak surface recombination velocity to surface recombination via amphoteric centers with larger capture cross-sections of charged centers than of neutral centers.
where [x.sub.j] is the junction depth, H is the thickness of the cell, [S.sub.n] is the back surface recombination velocity
of electrons and w is the space charge width.
Through the gated diode method, the surface recombination velocity
([s.sub.o]) and the minority carrier lifetime ([[tau].sub.FIJ]) in the field-induced depletion region can be extracted.
Green, "Surface recombination velocity measurements at the silicon-silicon dioxide interface by microwave-detected photoconductance decay," Journal of Applied Physics, vol.
Bock et al., "The surface recombination velocity at boron-doped emitters comparison between various passivation techniques," in Proceedings of the 21st European Photovoltaic Solar Energy Conference, pp.
where [S.sub.pass] is the surface recombination velocity
in passivated area, and [S.sub.cont] is the recombination velocity
at the contact, W is the substrate thickness, f is the metallization fraction, [rho] is the base resistivity, D is the carrier diffusion coefficient, and [R.sub.s] is the series resistance of the base.
Our results show that in addition to a low surface recombination velocity
of 1000 cm/s at back contact and a barrier height of 0.1 eV, an ER layer of 100 nm with a doping density of 7 x [10.sup.18] [cm.sup.-3] is also required to produce the best cell efficiency performance of 19.83% summarized in Table 5.