Trap Characterization in InAlN/GaN and AlN/GaN based HEMTs with Fe- and C-doped Buffers

Electrically active traps in InAlN/GaN and AlN/GaN based high-electron mobility transistors (HEMTs) with different buffer doping impurities are characterized by drain current transient (DCT) spectroscopy. A single deep-level trap at EC–0.63 eV (σ = ~6×10
^-15
cm
²
) is identified in the InAlN/GaN HEMT with Fe-doped buffer layer. The DCT experiments on InAlN/GaN HEMT (C-doped buffer) reveal an electron trap at E
C
–0.14 eV with a capture cross-section of 4×10
^-18
cm
²
. In AlN/GaN HEMT with C-doped buffer, a trap signature at EC–0.33 eV is observed with lower capture cross-section value of 2×10
^-20
cm
²
. The DCT spectra of the C-doped HEMT devices have shown Arrhenius-like behaviour in the emission time constants, suggesting that charging/discharging dynamics of these traps is not governed by the defect bands, instead the carrier exchange may occur between the particular trap level and the conduction band through SRH recombination.