Thermoelectric Design of Delta-Doped β-(Al_xGa_1–x)₂O₃/Ga₂O₃ Metal Insulator Semiconductor High-Electron Mobility Transistors

This work presents thermoelectric (TE) devices design of delta-doped <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-(AlxGa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{1}-{x}}$ </tex-math></inline-formula>)2O3/Ga2O3 metal insulator semiconductor high electron mobility transistors (MIS-HEMTs) using TCAD simulations. The TE properties of devices were comprehensively investigated with various temperature, gate voltages, gate lengths, delta-doping concentrations, and positions. With high delta-doping concentrations, a parasitic current channel is induced and that reduces electron chemical potential, resulting in high conductivity, a low Seebeck coefficient, and a reduced turn on voltage. Moving delta-doping positions closer to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-(AlxGa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{1}-{x}}$ </tex-math></inline-formula>)2O3/Ga2O3 interface enhances the concentration of the 2-D electron gas (2DEG), which screens the strong polar optical-phonon scattering and improves 2DEG mobility. For delta-doping positions at 1 nm, the power factor is improved due to quantum effect and energy filter effect, allowing the trade-off relationship between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma $ </tex-math></inline-formula> and S to be mitigated. Expanding gate lengths increases channel electron temperature at gate edge near drain side. These results provide valuable insights and crucial guidance for the design of high-performance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-(AlxGa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{1}-{x}}$ </tex-math></inline-formula>)2O3/Ga2O3 MIS-HEMTs for TE and temperature sensing applications.