High optical responsivity of InAlAs-InGaAs metamorphic high-electron mobility transistor on GaAs substrate with composite channels

The high optical responsivity of the InAlAs-InGaAs metamorphic high-electron mobility transistor on GaAs substrate with composite channels is reported. Experimental results verify that the photovoltaic effect causing the effective decrease of threshold voltage is responsible for the photoresponse to a 1.55-mum optical illumination.