High Electrical Resistivity $1.55~\mu$ m Photoconductive Switch Using a Barrier Structure

We propose a low temperature grown Be-doped InGaAs vertically aligned barrier structure to increase the dark electrical resistivity of the 1.55 μm photoconductive switch. The insertion of a 100 nm-thick AlAs
_0.56
Sb
_0.44
barrier layer with a large conduction band offset to In
_0.53
Ga
_0.47
As blocks the flow of the majority carrier. In this study, samples are grown using a molecular beam epitaxy system. I-V measurement shows that the effective dark electrical resistivity of the samples increases from 0.5Ωcm to 8.5 × 10
⁴
Ωcm. The increase of barrier thickness from 100 nm to 400 nm does not increase the dark electrical resistivity further. The photo-response of the samples is also measured and analyzed. This study demonstrates a new approach to achieve high electrical resistivity in a photoconductive switch.