Dynamics of the kink effect in InAlAs/InGaAs HEMTs

Abstract

Abstract-We have carried out pulsed measurements of the kink effect in InAlAs/InGaAs HEMT's on InP with nanosecond resolution. Our measurements show that the kink's characteristic time constant is strongly dependent on VDS, i.e., it drops by more than three decades, from 100 s down to 50 ns, between low and high values of V DS : This suggests that the kink should not be operational for frequencies in the microwave and millimeter wave regimes. We also find that the kink turn-on dynamics correlate with impact ionization. In particular, the inverse of the kink's characteristic time constant follows a classical impact ionization behavior.

A new physical model for the kink effect on InAlAs/InGaAs HEMTs

“…In order to test our model we have used lattice-matched, MBE-grown, HEMT's fabricated at MIT as a vehicle for this study [16], [18]. We examine devices with relatively long gate lengths ( m to m).…”

“…Additionally, simulations show that the kink disappears if the impact ionization mechanism is turned off in the simulator [3], [4], [15]. Finally, we have reported sidegate measurements establishing a direct relationship between impact ionization and the kink [16], [17], as well as transient measurements showing that the time constants associated with the kink are strongly correlated with the impact ionization rate [18].…”

“…6 plots the measured and predicted large signal transient behavior of the kink. These measurements were performed using a carefully designed pulsed current-voltage (I-V) setup on an MBE-grown InAlAs/InGaAs single heterostructure HEMT with m [18]. The measurement consists of pulsing the device from the off-state to the on-state along a 50 load line, and measuring the resulting terminal voltages and currents as a function of time.…”

“…• relationship between impact ionization and the kink [17]; • kink's dynamic behavior (particularly the bias-dependence of the time constants associated with the kink) [18]; • relationships between the kink and the recess (for example, why is the kink strengthened as the width of the source-side recess is increased?) [22], [25]; • kink's dependence on aging and surface treatments [5], [26].…”

“…[22], [25]; • kink's dependence on aging and surface treatments [5], [26]. We have recently carried out a several studies of the kink, including dc characterization [16], sidegate measurements [17], and large-signal transient measurements with nanosecond resolution [18]. In this work, we have combined the results of these measurements, as well as new measurements of the kink's temperature and illumination dependence, to develop a comprehensive picture of the kink.…”