Title: Minority carrier diffusion lengths and mobilities in low-doped n-InGaAs for focal plane array applications,
Abstract: The hole diffusion length in n-InGaAs is extracted for two samples of
different doping concentrations using a set of long and thin diffused junction
diodes separated by various distances on the order of the diffusion length. The
methodology is described, including the ensuing analysis which yields diffusion
lengths between 70 - 85 um at room temperature for doping concentrations in the
range of 5 - 9 x 10^15 cm-3. The analysis also provides insight into the
minority carrier mobility which is a parameter not commonly reported in the
literature. Hole mobilities on the order of 500 - 750 cm2/Vs are reported for
the aforementioned doping range, which are comparable albeit longer than the
majority hole mobility for the same doping magnitude in p-InGaAs. A radiative
recombination coefficient of (0.5-0.2)x10^-10 cm^-3s^-1 is also extracted from
the ensuing analysis for an InGaAs thickness of 2.7 um. Preliminary evidence is
also given for both heavy and light hole diffusion. The dark current of
InP/InGaAs p-i-n photodetectors with 25 and 15 um pitches are then calibrated
to device simulations and correlated to the extracted diffusion lengths and
doping concentrations. An effective Shockley-Read-Hall lifetime of between
90-200 us provides the best fit to the dark current of these structures.