Comparative study on characteristics of Si-based AlGaN/GaN recessed MIS-HEMTs with HfO₂ and Al₂O₃ gate insulators

【摘要】 Two types of enhancement-mode（E-mode） AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors（MIS-HEMTs） with different gate insulators are fabricated on Si substrates. The HfO₂ gate insulator and the Al₂O₃ gate insulator each with a thickness of 30 nm are grown by the plasma-enhanced atomic layer deposition（PEALD）. The energy band diagrams of two types of dielectric MIS-HEMTs are compared. The breakdown voltage（VBR） of HfO₂ dielectric layer and Al₂O₃ dielectric layer are 9.4 V and 15.9 V, respectively. With the same barrier thickness, the transconductance of MIS-HEMT with HfO₂ is larger. The threshold voltage（Vth） of the HfO₂ and Al₂O₃ MIS-HEMT are 2.0 V and 2.4 V, respectively, when the barrier layer thickness is 0 nm. The C–V characteristics are in good agreement with the Vth’s transfer characteristics. As the barrier layer becomes thinner, the drain current density decreases sharply. Due to the dielectric/Al Ga N interface is very close to the channel, the scattering of interface states will lead the electron mobility to decrease.The current collapse and the Ron of Al₂O₃ MIS-HEMT are smaller at the maximum gate voltage. As Al₂O₃ has excellent thermal stability and chemical stability, the interface state density of Al₂O₃/Al Ga N is less than that of HfO₂/AlGaN.更多还原

【Abstract】 Two types of enhancement-mode（E-mode） AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors（MIS-HEMTs） with different gate insulators are fabricated on Si substrates. The HfO₂ gate insulator and the Al₂O₃ gate insulator each with a thickness of 30 nm are grown by the plasma-enhanced atomic layer deposition（PEALD）. The energy band diagrams of two types of dielectric MIS-HEMTs are compared. The breakdown voltage（VBR） of HfO₂ dielectric layer and Al₂O₃ dielectric layer are 9.4 V and 15.9 V, respectively. With the same barrier thickness, the transconductance of MIS-HEMT with HfO₂ is larger. The threshold voltage（Vth） of the HfO₂ and Al₂O₃ MIS-HEMT are 2.0 V and 2.4 V, respectively, when the barrier layer thickness is 0 nm. The C–V characteristics are in good agreement with the Vth’s transfer characteristics. As the barrier layer becomes thinner, the drain current density decreases sharply. Due to the dielectric/Al Ga N interface is very close to the channel, the scattering of interface states will lead the electron mobility to decrease.The current collapse and the Ron of Al₂O₃ MIS-HEMT are smaller at the maximum gate voltage. As Al₂O₃ has excellent thermal stability and chemical stability, the interface state density of Al₂O₃/Al Ga N is less than that of HfO₂/AlGaN.更多还原