CHARACTERISTICS OF INALAS INGAAS HIGH-ELECTRON-MOBILITY TRANSISTORS UNDER 1.3-MU-M LASER ILLUMINATION/

The current-voltage (I-V) characteristics of InAlAs/InGaAs high electr on mobility transistors (HEMT's) under illumination are investigated. The change of the drain current caused by the illumination can be expl ained by using the photovoltaic effect so that the excess holes photo- generated in the InGaAs channel lager accumulate at the source-electro de region and cause an effective decrease in the potential barrier for electrons between the source and the channel, The basic equations des cribing this phenomenon are derived on the basis of the experimental r esults. In addition, our experimental results are shown to support the barrier-induced hole pile-up model in which holes generated by the im pact ionization accumulate in the InAlAs barrier on the source side an d cause the kink effect in InAlAs/InGaAs HEMT's.