Intense terahertz emission from GaAs and InAs thin films grown on GaSb substrates

We report on the terahertz (THz) emission from n-GaAs/p-GaSb and /p-InAs/n-GaSb structures using a 1.55 μm femtosecond laser excitation. The effect of the n-GaAs thin film on a p-GaSb substrate is investigated. Significant THz emission from n-GaAs/p-GaSb compared to bare p-GaSb is observed and could be attributed to the built-in field at the interface of the sample. The comparison with a bulk p-InAs and p-InAs/n-GaSb indicates n-GaAs/p-GaSb is a strong THz emitter comparable with those InAs-based emitters.