Study on the electron mobility related with ohmic contact width in AlGaN/GaN HEMTs

Abstract

For the fabricated AlGaN/GaN high electron mobility transistors (HEMTs) with different Ohmic contact widths, the gate-channel electron mobility is obtained experimentally. Mobility curves show very different values and trends. This phenomenon is investigated with the scattering theory in AlGaN/GaN HEMTs. The reason for the different mobility curves is found to be attributed to the different polarization charge distributions at the AlGaN/GaN interface. The AlGaN/GaN HEMT with a smaller Ohmic contact width corresponds to positive additional polarization charge near the Ohmic contact. The AlGaN/GaN HEMT with a larger Ohmic contact width corresponds to negative additional polarization charge near the Ohmic contact. Changing the Ohmic contact width will be a new dimension to optimize the characteristics of AlGaN/GaN HEMTs effectively.