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.

Influence of Proton Irradiation Energy on Gate–Channel Low-Field Electron Mobility in AlGaN/GaN HEMTs

“…For devices in the same proton irradiation environment, the variation of µn should be consistent under the influence of the first four scattering mechanisms after proton irradiation, which is inconsistent with the experimental results (Figures 6 and 7). Previous studies have reported that PCF scattering is closely related to device size [19][20][21][22][23]28,29]. Therefore, although µn is dominated by POP scattering at room temperature, the differences in µn behavior corresponding to the different LGD (Figures 6 and 7) must be attributed to PCF scattering.…”

“…A change of the lattice structure, which is induced by the displacement effect, will inevitably affect the polarization charge distribution by changing the strain distribution. It has been proven that the polarization Coulomb field (PCF) scattering is a special and important scattering mechanism in AlGaN/GaN HEMTs, and the PCF scattering is directly related to the device size and polarization charge distribution at the AlGaN/GaN interface [19][20][21][22][23]. Therefore, proton irradiation will alter the electron mobility of AlGaN/GaN HEMTs and device performance through PCF scattering.…”

Proton irradiation influence on gate-channel low-field carrier mobility of AlGaN/GaN HEMTs

“…However, what is different for AlGaN/GaN HEMTs, is that the displacement damage will inevitably change the strain distribution at the AlGaN/GaN interface, which may in turn affect the polarization charge distribution. The polarization charge distribution is closely related to carrier mobility in the view of polarization Coulomb field (PCF) scattering, which has been proven as an important and specific scattering mechanism in AlGaN/GaN HEMTs [15][16][17][18][19]. PCF scattering originates from the nonuniform polarization charges at the AlGaN/GaN interface and is directly related to the device size.…”