A method for determining a recombination characteristic at a semiconductor surface, wherein the method comprises: providing a test structure, wherein the test structure comprises: a semiconductor substrate having a first surface and a second surface opposite to the first surface; a first passivation layer on the first surface; a second passivation layer on the second surface, the second passivation layer having a plurality of openings at predetermined locations; and a plurality of metal features in contact with the second semiconductor surface at the predetermined locations, thus forming metallized surfaces at the predetermined locations and non-metallized surfaces outside the predetermined locations, wherein a characteristic size of the metal features is smaller than an effective diffusion length in the underlying semiconductor at the predetermined locations, and the metal features being provided with a spacing smaller than an effective diffusion length in the underlying semiconductor outside the predetermined locations, the metal features being grouped in a plurality of zones, each of the plurality of zones having a different metal coverage, the metal coverage being the ratio between the metallized surface area and the total area; performing a photo-conductance decay measurement in each of the plurality of zones, thereby determining effective lifetimes for different injection levels as a function of metal coverage; and extracting the recombination characteristic from the measured effective lifetimes. providing a test structure, wherein the test structure comprises: a semiconductor substrate having a first surface and a second surface opposite to the first surface; a first passivation layer on the first surface; a second passivation layer on the second surface, the second passivation layer having a plurality of openings at predetermined locations; and a plurality of metal features in contact with the second semiconductor surface at the predetermined locations, thus forming metallized surfaces at the predetermined locations and non-metallized surfaces outside the predetermined locations, wherein a characteristic size of the metal features is smaller than an effective diffusion length in the underlying semiconductor at the predetermined locations, and the metal features being provided with a spacing smaller than an effective diffusion length in the underlying semiconductor outside the predetermined locations, the metal features being grouped in a plurality of zones, each of the plurality of zones having a different metal coverage, the metal coverage being the ratio between the metallized surface area and the total area; a semiconductor substrate having a first surface and a second surface opposite to the first surface; a first passivation layer on the first surface; a second passivation layer on the second surface, the second passivation layer having a plurality of openings at predetermined locations; and a plurality of metal features in contact with the second semiconductor surface at the predetermined locations, thus forming metallized surfaces at the predetermined locations and non-metallized surfaces outside the predetermined locations, wherein a characteristic size of the metal features is smaller than an effective diffusion length in the underlying semiconductor at the predetermined locations, and the metal features being provided with a spacing smaller than an effective diffusion length in the underlying semiconductor outside the predetermined locations, the metal features being grouped in a plurality of zones, each of the plurality of zones having a different metal coverage, the metal coverage being the ratio between the metallized surface area and the total area; performing a photo-conductance decay measurement in each of the plurality of zones, thereby determining effective lifetimes for different injection levels as a function of metal coverage; and extracting the recombination characteristic from the measured effective lifetimes.