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

Abstract

The kink effect in InAlAs/InGaAs/InP composite channel heterojunction field effect transistors (HFET's) was investigated as a function of temperature and optical excitation. Drain source and gate current measurements show that above 325 K the kink effect disappears while the impact ionization process is still present. The kink at low temperatures is suppressed by illumination with photons of energy above 1 eV. These results prove that this parasitic effect is mainly related to the presence of traps in the top layers.

Correlation between static characteristics and deep levels in InAlAs/InGaAs/InP HEMT'S

“…Some studies have established a link between the kink effect and impact ionization phenomena occurring in the InGaAs channel [12], while other studies have correlated this effect with the presence of traps in the structure [13][14][15]. This is why a detailed study of electrically active defects is necessary in order to understand the origin of the non-ideal current voltage characteristics.…”

Single- and double-heterostructure GaN-HEMTs devices for power switching applications

“…6). When sweeping V DS from 0 V towards higher voltages light improves I D due to photo-assisted detrapping [10]; during sweep from high-to-low voltages no relevant kink is present, thanks to the previous high field assisted detrapping during the low-to-high V DS sweep. The n-type SiC is more prone to kink effect that can hence be attributed to the substrate; the influence of GaN capping layer is however under investigation and no data are available at the time of this publication.…”

“…Wafer A and D share the same substrate, nucleation and barrier layers; A has a GaN buffer layer, D is a DH with a GaN channel layer over a AlGaN back barrier layer [9][10][11]. C and E have been built both on semi-insulating substrate, have similar barrier layers, and the same n-type Si-doped cap.…”

Physical investigation of trap-related effects in power HFETs and their reliability implications

“…Several interpretations of the kink effect have appeared over the years, based on a wide range of experimental observations and a fair amount of different materials and technologies. Just to quote some recent papers, these include elimination of self-sidegating due to the gate pad due to holes [12], accumulation of free holes in the channel and hole capture in the buffer [12], capture and emission of electrons through traps in the buffer [12], trapping and detrapping by deep levels in the top layers [13], or by surface states between gate and source [14], hole pileup on the source side with no trap effects [15], and hole trapping by surface states between gate and drain or by substrate traps [16]. This brief and partial literature review shows that, while there is a general consensus on impact ionization and hole generation being a necessary condition for the kink, the whole mechanism that triggers the kink seems to be technology-dependent and different for PHEMTs [12], InP HEMTs [13]- [15], and GaAs MESFETs [16].…”