Determination of nonuniform diffusion length and electric field in semiconductors

A method is proposed that purports to measure the non-uniform diffusion length
L(x)
in the presence of an arbitrary electric field
E_{x}(x)
. A point source of carrier generation (as a model for an electron beam) scans across the sample in the thickness direction x while the induced currents are measured at two reverse-biased junctions sandwiching the sample.
L(x)
and
(E_{x} \micro_{p} + D_{p})/D_{p}
can be deduced from the currents. If only one collecting junction is present, one of the two functions may be deduced provided that the other is known; in addition, the surface recombination velocity at the other boundary may be determined in the presence of arbitrary
L(x)
and
E_{x}(x)
. With additional scanning in the
y
and
z
directions, quasi three-dimensional mapping is possible.