Characteristics of InAlAs/InGaAs high electron mobility transistors under 1.3-μm laser illumination

The current-voltage (I-V) characteristics of InAlAs/InGaAs high electron mobility transistors (HEMTs) under illumination are investigated. The change of the drain current caused by the illumination can be explained by using the photovoltaic effect so that the excess holes photo-generated in the InGaAs channel layer accumulate at the source-electrode region and cause an effective decrease in the potential barrier for electrons between the source and the channel. The basic equations describing this phenomenon are derived on the basis of the experimental results. In addition, our experimental results are shown to support the barrier-induced hole pile-up model in which holes generated by the impact ionization accumulate in the InAlAs barrier on the source side and cause the kink effect In InAlAs/InGaAs HEMTs.