Photo‐Hall measurements on laser‐generated electron‐hole plasmas in Hg1−xCdxTe

Photo‐Hall techniques have been employed to study mobilities in photoexcited n‐type Hg1−xCdxTe (x≊0.2) at low temperatures (T≊10 K). Excitation is provided by pulses of either 25 μs or 200 ns duration from a CO2 laser. At low excitation levels, acceptor neutralization causes the mobility to increase in a manner sensitive to the degree of compensation present in the sample. At higher excitation the mobility decreases monotonically due to electron‐hole scattering. Comparison is made to a transport theory for optically generated plasmas in semiconductors with nonparabolic bands. The calculation includes a partial‐wave phase shift treatment of ionized impurity and electron‐hole scattering, screening by the photoexcited carriers, and alloy scattering. At high excitation levels the mobility is found to depend strongly on the ’’dynamic’’ nature of the free carrier screening of electron‐hole interactions.