Al mole fraction dependence of deep levels in AlGaN/GaN-HEMT structures estimated by CV profiling


Current-voltage (IV) measurements and capacitance-voltage (CV) measurements have been carried out to investigate electrical properties of AlGaN/GaN-HEMT structures. By CV measurements of Schottky barrier diodes (SBDs) with large leak currents, we observed a distinct peak in CV profiling at low frequencies. The integral of this peak was found to have a correlation with a leak current. The behavior of this peak might be described by the Shockley-Read-Hall (SRH) model if we assume this peak is due to a phenomenon of an electron emission and capture by deep levels. Then Quasi-Fermi Level (Imref) at the bias point where this peak appears in CV profiling corresponds to energy depth of deep levels. That energy level can be approximated by Imref of two-dimensional (2D) electron gas. The result of our samples showed that the energy depth of deep levels from the conduction band is distributed from 320meV to 470meV for Al mole fraction from 0.19 to 0.30, respectively.


  1. X Yu, E. S. Yang, and H. L. Evance, J. Appl. Phys. 68, 2845 (1990)

    Article  Google Scholar 

  2. J. H. Werner, R. T. Tung, A. F. J. Levi, M. Anzlowar, and M. Pinto, Phys. Rev. Lett. 60, 53 (1988)

    CAS  Article  Google Scholar 

  3. T. Yamada, M. Iwami, K. Imada, T. Tsuchiya, J. Kikawa, Y. Hiroyama, T. Araki, A. Suzuki, and Y. Nanishi, Extended Abstracts (The 51st Spring Meeting, 2004), The Japan Society of Applied Physics, 31p-V-6

  4. T. Ohori, M. Takikawa, and J. Komeno, J. Appl. Phys. 63, 1223 (1988)

    CAS  Article  Google Scholar 

  5. M. S. Shur, Mater. Res. Soc. Symp. Proc., 483, 15 (1998)

    CAS  Article  Google Scholar 

  6. J. Schmitz, N. Cubaynes, R. J. Havens, R. de Kort, A. J. Scholten, and L. F. Tiemeijer, IEEE Semic. Manuf. 17 150 (2004)

    Article  Google Scholar 

Download references


This work was carried out under High-Power, High Frequency Gallium Nitride Device Project of NEDO, Japan.

Author information



Corresponding author

Correspondence to Junjiroh Kikawa.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kikawa, J., Imada, K., Yamada, T. et al. Al mole fraction dependence of deep levels in AlGaN/GaN-HEMT structures estimated by CV profiling. MRS Online Proceedings Library 892, 1001 (2005).

Download citation