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

摘要

Deep-level traps in AlGaN/GaN- and 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 Al0.25Ga0.75N/GaN HEMT (Fe-doped buffer) reveal a single electron trap at E-C -0.47 eV. On the other hand, an electron trap at E-C - (0.53-0.59) eV and a deep hole trap at E-V + 0.82 eV are detected in Al0.845In0.155N/AlN/GaN HEMT with unintentionally doped (UID) buffer, while a slow detrapping behavior is noticed at E-C -0.6 eV in Al0.83In0.17N/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.