No abstract

No abstract

The sensitivity of a contactless measurement procedure to determine the minority-carrier recombination parameters in Si wafers is analyzed. The measurement is based on the harmonic generation of excess carriers, whose time dependence is measured either by μ-wave reflection or free-carrier absorption. Both the measurement equipment and the model used to extract the surface recombination velocity and the bulk carrier lifetime are introduced and the sensitivity of the parameter fit procedure is examined. The results of this uncertainty analysis are applied to typical experimental situations, e.g., bulk minority carrier lifetime measurement of a monocrystalline wafer with equal surfaces or a bulk minority carrier lifetime mapping done on an as-grown multicrystalline Si wafer before it obtained saw damage removal. The method proves to be very useful, if the interpretation of the results is carefully done and an appropriate experiment is chosen to produce the best possible results.

We present a new technique for boron (B) doping of silicon. In this letter we show that a B doping profile of more than 2 μm thickness with a maximum active doping concentration of 3×1019 cm−3 can be formed by a fast (<1 min) alloying process at a temperature of 850 °C. Thick-film aluminum is used to obtain an alloying and epitaxial regrowth process in accordance with the Al–Si phase diagram. The atomic concentration profile of the B- and Al-doped Si layer was determined by secondary ion mass spectrometry. The active doping concentration was measured with an automatic electrochemical capacitance/voltage profiler. By the addition of B to the Al paste, the epitaxially regrown layer is doped with B and Al to the solid solubility of these elements in Si at the particular regrowth temperature. The applicability of this fast low temperature B doping process in Si solar cell processing is discussed.

No abstract