Examination of the kink effect in InAlAs/InGaAs/InP HEMTs using sinusoidal and transient excitation

The kink effect in InAlAs/InGaAs/InP HEMTs is examined in the frequency domain using sinusoidal excitation and in the time domain using voltage pulses applied to the drain of the devices. With the sinusoidal excitation below the kink voltage, two prominent output-resistance frequency-response transitions attributed to traps in the InAlAs or its interfaces were found. These transitions were examined as functions of temperature and yielded trap activation energies near 0.18 and 0.56 eV. Above the kink voltage, a single, broad transition with an activation energy near 0.24 eV was found. Using incremental voltage pulses applied to the drain, a convenient kink signature was obtained. With large voltage pulses which span the kink region, a complex nonexponential transient response was observed due to concurrent capture and emission mechanisms. HEMTs with single- and double-recessed gate structures were found to have similar output resistance dispersion characteristics.