Iron-induced deep-level acceptor center in GaN/AlGaN high electron mobility transistors: Energy level and cross section

Abstract

Dynamic transconductance dispersion measurements coupled with device physics simulations were used to study the deep level acceptor center in iron-doped AlGaN/GaN high electron mobility transistors (HEMT). From the extracted frequency dependent trap-conductance, an energy level 0.7 eV below the conduction band and a capture cross section of 10−13 cm2 were obtained. The approach presented in this work avoids the non-equilibrium electrical or optical techniques that have been used to date and extracts the device relevant trap characteristics in short channel AlGaN/GaN HEMTs. Quantitative prediction of the trap induced transconductance dispersion in HEMTs is demonstrated.

Traps localization and analysis in GaN HEMTs

“…On the other hand, thermally corrected data-points (open-symbols) are nicely overlapping for all three FE devices. The extracted activation energies for FE devices were very close to each other ranging from 0.57 eV to 0.59 eV, falling within the 0.5 eV [4]À0.7 eV range [5] typically associated with defects related to the Fe-doping of GaN layer, strongly suggesting that the main cause of current dispersion in all FE devices tested might be related to the Fe-doped GaN buffer. Although the extracted activation energies were very close to each-other, the traps capture cross-section varied from approximately 5 Â 10 À15 to 2 Â 10 À14 cm À2 .…”

Intentionally Carbon-Doped AlGaN/GaN HEMTs: Necessity for Vertical Leakage Paths

“…To measure this in the wafers studied and calibrate the model, we used small-signal transconductance (g m ) dispersion. This technique measures the frequency dependence of the loss-angle in the transconductance and is sensitive to trap states located under the gate [14,15]. The dispersion arose here as a result of a simple R-C network where R was the distributed resistance of the buffer and C the capacitance of the depletion region under the gate.…”

“…3. The small-signal g m dispersion was then simulated with Silvaco ATLAS using the same approach as [7,15] with the results shown overlaid in Fig. 3.…”

High‐resistance GaN‐based buffer layers grown by a polarization doping method

“…Other than these, the most widely method to inhibited the drain leakage is impurity doping. The acceptor impurity, such as C, Fe, Mg and Mn, is intentionally introduced to provide holes to compensate the background electrons [7][8][9][10]. However, many research show that intentional doping could bring the high density defect traps, which result in an increase in the ON-resistance during switching operation,so-called current collapse [11,12].…”