Photoconductivity in PbTe nipi
structures
One of the most interesting effects of nipi structures is the lifetime enhancement of excess carriers due to the built
in bandedge modulation which separates the optically generated e-h-pairs in space and finally leads to an
enhancement of the response. However the lifetime enhancement generally slows down the detector speed. We
present a nipi based detector concept which takes advantage of the enhanced response, but at the same time allows
to reduce the response time far below the characteristical lifetime in such structures. The physical background of
the concept is presented in a theoretical model which can be understood in terms of the enhanced ambipolar
diffusion and the local control of the balance of carrier generation and recombination by applying a lateral external
current between two selective contacts. Results of numerical simulations are compared to experimental data
obtained from selectively contacted PbTe single period (p-n-p) nipi-structures.
For more detailed information