Sinusoidal and transient response of traps in double-recessed InAlAs/InGaAs/InP HEMTs

The effects of trapping mechanisms on the transconductance and output resistance of InAlAs/InGaAs/InP high-electron mobility transistors (HEMTs) with a double-recessed gate structure are reported. The results at nominal bias conditions and room temperature indicate an increase of transconductance with frequency of about 15% occurring primarily between 100 Hz and 1 MHz and an almost constant output resistance. The output resistance, however, has a complex dispersion behavior in the vicinity of the kink effect. The detailed characteristics of the dispersion involve several transition frequencies and associated time constants with different activation energies and having electric field dependence. Transient response measurements with both gate and drain inputs give results consistent with the sinusoidal response. The activation energies of the most prominent trapping effects were determined by measuring the time constants or transition frequencies as functions of temperature