A slow-trap model for the kink effect on InAlAs/InP HFET

New aspects and mechanism of kink effect in InAlAs/InGaAs/InP inverted HFETs

“…The behavior of the characteristics in the 100-350 K range was studied and found to be similar to the one observed in InP channel HFET's [7]. Fig.…”

“…Experimental results have confirmed that the kink effect has a complex behavior: it starts to decrease at low frequencies (10-100 Hz) and is absent at higher frequencies [7], [8]. It can be suppressed using low-temperature buffers [6] or using silicon nitride passivation [9], it disappears when the device is heated [7] and there is a correlation between impact ionization and the kink effect [10]. Composite InGaAs/InP/InAlAs FET's are especially sensitive to kink effects and to frequency dispersion of drain conductance [11].…”

“…Some authors suggested that impact ionization is responsible for this effect [4], [5], while others attributed the kink effect to traps [3], [6]. Experimental results have confirmed that the kink effect has a complex behavior: it starts to decrease at low frequencies (10-100 Hz) and is absent at higher frequencies [7], [8]. It can be suppressed using low-temperature buffers [6] or using silicon nitride passivation [9], it disappears when the device is heated [7] and there is a correlation between impact ionization and the kink effect [10].…”

“…Thus, a hole pile-up is formed reducing the ohmic drop at the source and leads to an increase of . However, we have also observed the kink effect in InP channel HFET's [7], where the impact ionization component was not detected on the gate current.…”

“…The disappearance of the kink at high temperature or by increasing the frequency measurement is explained in terms of trapping/detrapping mechanism [7]. In this model, the kink is associated to a parasitic space charge region due to traps filled, at low temperature, by electrons when .…”