Influence of Al₂O₃ Oxide Layer Thickness Variation on PZT Ferroelectric Al_0.3Ga_0.7N/AlN/GaN E-Mode GR-MOSHEMT

The dielectric oxide Al₂O₃ induced gate recessed PZT ferroelectric Al_0.3Ga_0.7N/AlN/GaN MOSHEMT device behavior with different oxide thicknesses is analyzed in this work. The stack of different layers Al₂O₃/Al_0.3Ga_0.7N/AlN/GaN is grown on a silicon (Si) substrate. Gate recessed technique is used for achieving the normally off operation in the MOSHEMT. Normally off devices provide better control in gate leakage current and stability of threshold voltage (V_th). The ferroelectric material of lead zirconate titanate Pb(Zr,Ti)O₃ (PZT) is induced between the gate and oxide layer to obtain the enhancement type (E-Mode) operation to improve the device performance due to the strong polarization effect. The AlN spacer layer is introduced between the Al_0.3Ga_0.7N barrier and GaN Channel to increase mobility and 2-DEG confinement. For controlling the GaN channel layer, the AlN nucleation layer is inserted between GaN/Si–substrate interfaces by producing better surface morphology. Furthermore, silicon-based substrates are used to achieve excellent thermal characteristics. Due to the polarization effect, a two-dimensional electron gas (2-DEG) is created at the Al_0.3Ga_0.7N/GaN interface. The analog performance parameters like drain current (I_d), output characteristics (I_d − V_d), transconductance (gm), cutoff frequency (f_T), and gate-to-source capacitance (C_gs) except maximum frequency of oscillation (F_max) show an improvement for 3 nm oxide layer thickness of Al₂O₃. The results of the proposed device Al_0.3Ga_0.7N/AlN/GaN PZT GR-MOSHEMT shows an impact on high power and RF-based devices. All the simulations are done by the commercial Silvaco Atlas Technology Computer-Aided Design (TCAD) tool.