Electron mobility in the linear region of AlGaN/AlN/GaN heterostructure field-effect transistor

We simulate the current-voltage (I-V) characteristics of the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate lengths using the quasi-two-dimensional (quasi-2D) model. The calculation results obtained using modified mobility model are found to accord well with the experimental data. By analyzing the variation of the electron mobility for the two-dimensional electron gas (2DEG) with the electric field in the linear region of the AlGaN/AlN/GaN HFET I-V output characteristics, it is found that the polarization Coulomb field scattering still plays an important role in the electron mobility of AlGaN/AlN/GaN HFET at the higher drain voltage and channel electric field. As drain voltage and channel electric field increase, the 2DEG density reduces and the polarization Coulomb field scattering increases, as a result, the 2DEG electron mobility decreases.