Introduction Recombination at the surface of a silicon solar cell is an important factor in determining the cell efficiency. The descriptive parameter is surface recombination velocity, s. Generally, s increases as the doping of the surface increases, just as the lifetime of carriers within the crystal (τ) generally decreases as the bulk doping increases. Thus, in a comparative study of candidate surface treatments, it is important to choose a silicon surface doping level which is typical of common cell designs. Furthermore, because standard measurement techniques cannot distinguish between recombination at the crystal surface and recombination within the crystal bulk, it is desirable to choose a silicon crystal with high bulk lifetime in order to improve the sensitivity of the technique to surface recombination. In this study, 100 mm diameter float zone (FZ) silicon wafers, double side polished, with a (100) surface and 300 μm thickness were chosen: p-type (boron-doped) nominally 3 Ω-cm and n-type (phosphorus-doped) nominally 1.2 Ω-cm. The primary comparison was made between surfaces passivated with a thermally-grown oxide and those passivated with amorphous silicon deposited by the hot wire method. In addition, the degree of surface passivation associated with the thin chemical oxide created by RCA cleaning was measured, as was that associated with a temporary iodine-methanol treatment.