Publications

Minority carrier lifetimes in very long-wave infrared InAs/GaInSb superlattices

Haugan, Heather J.; Brown, Gail J.; Olson, Benjamin V.; Kadlec, Emil A.; Kim, Jin K.; Shaner, Eric A.

Significantly improved carrier lifetimes in very-long wave infrared InAs/GaInSb superlattice (SL) absorbers are demonstrated by using time-resolved microwave reflectance (TMR) measurements. A nominal 47.0 Å InAs/21.5 Å Ga0.75In0.25Sb SL structure that produces an approximately 25 μm response at 10 K has a minority carrier lifetime of 140 ± 20 ns at 18 K, which is markedly long for SL absorber with such a narrow bandgap. This improvement is attributed to the strain-engineered ternary design. Such SL employs a shorter period with reduced gallium in order to achieve good optical absorption and epitaxial advantages, which ultimately leads to the improvements in the minority carrier lifetime by reducing Shockley-Read-Hall (SRH) defects. By analyzing the temperature-dependence of TMR decay data, the recombination mechanisms and trap states that currently limit the performance of this SL absorber have been identified. The results show a general decrease in the long-decay lifetime component, which is dominated by the SRH recombination at temperature below ∼30 K, and by Auger recombination at temperatures above ∼45 K.