LOW SURFACE RECOMBINATION VELOCITIES ON DOPED SILICON AND THEIR IMPLICATIONS FOR POINT CONTACT SOLAR CELLS.

Surface recombination velocities (SRVs) have been measured on p-type silicon with high bulk lifetime, and an empirical relationship between dopant concentration and SRV was found. The SRV values measured on doped silicon with no doping grading range from 100 cm/s to 34 cm/s for boron concentrations of 1. 3 multiplied by 10**1**7 atoms/cm**3 and 4. 0 multiplied by 10**1**5 atoms/cm**3, respectively. These values are lower than those generally used for modeling high-low junctions. SRV increases with decreasing n//e, the excess photogenerated electron concentration at the Si/SiO interface. These data are used to predict J//0, the reverse saturation current, for surfaces that are shielded by back surface fields produced by high-low junctions. Emitter modeling indicates that it is possible to achieve values of J//0 in the neighborhood of 1 multiplied by 10**-**1**4 A/cm**2. Because of the strong dependence of the efficiency of a point contact solar cell operating at one sun on carrier recombination at the surface, surface diffusions that have a J//0 of 1 multiplied by 10**-**1**4 A/cm**2 would boost the efficiency significantly.