Deep-Level Traps in AlGaN/GaN- and AlInN/GaN-Based HEMTs With Different Buffer Doping Technologies

Deep-level traps in AlGaN/GaNand AlInN/GaN-based HEMTs with different buffer doping technologies are identified by drain current transient spectroscopy (DCTS) and low-frequency (LF) output admittance (Y
₂₂
) dispersion techniques. TCAD simulations are also carried out to determine the spatial location and type of traps. The DCTS and LF Y
₂₂
measurements on Al
_0.25
Ga
_0.75
N/GaN HEMT (Fe-doped buffer) reveal a single electron trap at EC - 0.47 eV. On the other hand, an electron trap at E
_C
- (0.53-0.59) eV and a deep hole trap at EV + 0.82 eV are detected in Al
_0.845
In
_0.155
N/AlN/GaN HEMT with unintentionally doped (UID) buffer, while a slow detrapping behavior is noticed at E
_C
- 0.6 eV in Al
_0.83
In
_0.17
N/AlN/GaN HEMT with C-doped buffer. The DCTS and LF Y
₂₂
measurements yield nearly the same trap signatures, indicating the reliability of the trap characterization techniques used in this article. The simulated LF Y
₂₂
characteristics show that all these traps are acceptor-like states located in the buffer layer. The identified trap parameters in various buffers may be helpful to improve the crystalline quality of the epitaxial buffer layers.