Mechanism of kink effect related to negative photoconductivity in AlGaAs/GaAs HEMTs

The observation and proposed mechanism for negative photoconductivity leading to the kink effect in the output DC characteristics of AlGaAs/GaAs HEMTs is reported. Negative photoconductivity is the result of trapping electrons at the surface, and the kink is attributed to the tunnelling of these trapped electrons back into the n-AlGaAs layer, at a constant gate-to-drain bias.