Trap characterization of microwave GaN HEMTs based on frequency dispersion of the output-admittance

Abstract

This paper presents a characterization method of traps in GaN HEMTs, based on the frequency dispersion of the output-admittance characterized by low-frequency S-parameter measurements. As RF performances of GaN HEMTs are significantly affected by trapping effects, trap characterization is essential for this power technology. The proposed measurement setup and extraction method allow us to derive the activation energy E a and the capture cross section σ n of the identified traps. A 0.25µm gate length InAlN/GaN HEMT was characterized. A trap was identified with an activation energy of 0.38eV, a capture cross-section of 1.73x10 -16 cm 2 , and a field dependency of the emission rate. These results are used to give an efficient feedback to the technology developments.

On Neural Networks Based Electrothermal Modeling of GaN Devices

“…17 shows the real and imaginary measured values of Y ds for the same investigated 1-mm GaN HEMT. These measurements agree well with the reported ones in [33], [34] and show the expected multiple traps and the typical positive dispersion (growth of out-put conductance with increasing the frequency). The trap mission time constants can be extracted from the frequencies of the peaks of Imag[Y ds ] or inflexion points of Real [Y ds ].…”

“…The trapping induced out-put conductance dispersion can be characterized by low frequency (fraction of MHz) measurements of Y ds [33]. For the considered device, under active bias condition, C gs has values in the order of 1 pF; while G gsf is in the order of 1 mS [34].…”

“…From Fig. 17 the estimated time constant is equal to 1 2π×1.2×10 5 = 1.3µs [33]. The measurements have been repeated at different bias conditions.…”

Electric Field and Self-Heating Effects on the Emission Time of Iron Traps in GaN HEMTs

“…Concerning the role of temperature, it is well known that the emission of an electron from an impurity level to the conduction band is a thermally activated process with activation energy Ea=Ec-Et and emission time constant τ, mutually related by the Arrhenius equation [16]. Accordingly, the net rate of carrier emission from traps is strongly temperature dependent, and this correlation is typically employed to extract Ea from measurements at different ambient temperatures.…”

Characterization and Electrical Modeling Including Trapping Effects of AIN/GaN HEMT 4×50μm on Silicon Substrate

“…The output admittance low frequency dispersion allows to identify the deep energy level effects [4]. The variables of the trap models, inside the current source, are adjusted in order to reproduce the Y22 imaginary part dispersion without impacting the DC and small signal modeling which has been already achieved.…”