Magneto-optics of InAs/GaSb superlattices

摘要

We investigate the optical and electrical properties of a series of InAs/GaSb superlattices (SLs) as a function of InAs layer width d, from 21 to 55 A, with a fixed GaSb layer width of 24 A, corresponding to SLs with the cutoff wavelengths between 4 and 19 μm. Since the higher electron mass in InAs/GaSb SLs than in mercury cadmium telluride should lead to lower photodiode tunneling currents, we also measured the cyclotron effective mass for a very long wavelength infrared design SLs. For d<40 A, the SLs were p-type, with hole mobilities of approximately 8 000 cm~2/V s. For a high mobility p-type sample no hole cyclotron resonance signal was detected. However, the SLs with d≥40 A were n-type, with electron mobilities increasing from 865 to 6126 cm~2/V s. Cyclotron resonance data on an n-type SL sample yielded an electron cyclotron mass of 0.068 m_0, which is three times the InAs bulk value of 0.023 m_. The mass enhancement was only partially accounted for by conduction band nonparabolicity, based on our 8×8 envelope function calculation.