Fabrication and characterization of modulation-doped β-(AlxGa1−x)2O3/Ga2O3 tri-metal FET utilizing ultra-high vacuum deposition based on plasma-assisted molecular beam epitaxy

Abstract

This study investigates the design of MOD-FETs (modulation-doped field effect transistors) using β-Ga₂O₃ as the substrate material. The main focus is on understanding the impact of self-heating on the alteration of mobility of electrons profile. This paper introduces a model that takes into account the influence on temperature and doping on the electron mobility in β-Ga₂O₃. Furthermore, it offers estimations for the conductivity of heat of β-Ga₂O₃, considering the influence of temperature and crystalline orientation. Furthermore, we showcase a practical example of modulation-doped β-(Al_xGa_1-x)₂O₃/Ga₂O₃ using a tri-metal FET where the energy level difference between the conduction bands and the presence of undesired channels in the barrier layer determines the maximum sheet carrier density in this structure. These channels enable the transfer of electrons from both the bottom and upper portions of the β-Ga₂O₃ quantum well. Using modulation doping, the proposed structure exhibited an ultimate current drain of 250 mA/m, a peak conductivity of 40 ms/m, and a potential of 10.0 V at ambient temperature. The electrical characteristics of the TMG device were evaluated by comparing it to the double-metal gate (DMG) device using the Atlas Silvaco TCAD simulation for analysis of performance. The results indicate that, the suggested device exhibits greater efficiency in terms of conductivity, current gain cut-off frequency, and energy gain cut-off frequency as compared to DMG transistors. The measured electric field in this example is a consequence of using a Tri-Metal Gate architecture (TMG) to regulate the channel. The designed setup achieves peak frequency of 45.5/50.5 gigahertz with a gate length of 0.2 mm. This discovery highlights the potential of using the β-(Al_xGa_1−x)₂O₃/Ga₂O₃ with tri-metal FET architecture as a promising method for high-power radio frequency operations.