【Device Papers】Lattice-matched nitride-oxide HEMTs with superior electronic and thermal performance

      Researchers from Indian Institute of Technology Kanpur have published a dissertation titled " Lattice-matched nitride-oxide HEMTs with superior electronic and thermal performance " in Journal of Applied Physics.

Abstract

      β-Ga₂O₃ has gained significant interest for applications in high-power devices because of its large energy bandgap of E_g = 4.4–4.8 eV, a high breakdown field of ∼7–8 MV/cm, and availability of melt-grown large area bulk substrates. (Al_xGa_1−x)₂O₃/Ga₂O₃-based heterostructure devices have also been realized for high-power and high-frequency applications. The performance of these devices is, however, limited by the low conduction band offsets resulting from difficulties in growing high-Al composition β-(Al_xGa_1−x)₂O₃. Additionally, low thermal conductivity of β-Ga₂O₃ can result in severe self-heating effects and potential early failure of devices, restricting its application in high temperature and high-power electronics. In this work, an in-depth analysis of lattice mismatch in the heterojunctions between (0001) oriented III-nitrides (AlN, GaN, BN, and InN) and （-201） oriented β-phase III-sesquioxides (Al₂O₃, Ga₂O₃, and In₂O₃) and their alloys is conducted. An AlN/β-(In_0.21Ga_0.79)₂O₃ heterojunction is found to have good lattice match with high conduction band offset along with a polarization charge induced 2-dimensional electron gas (2DEG) at the interface with density ∼23× the theoretically maximum 2DEG carrier density achievable in β-(Al_0.2Ga_0.8)₂O₃/Ga₂O₃ interface. Through detailed thermal simulations under different cooling conditions, we show significantly lower self-heating effect (R_TH reduction of ∼41%) in AlN/β-(In_0.21Ga_0.79)₂O₃ high electron mobility transistors (HEMTs) compared to β-(Al_0.2Ga_0.8)₂O₃/Ga₂O₃-based HEMTs. Additionally, a physics-based compact model is used to calculate practically achievable current density in the presence of self-heating effects in these structures. For similar temperature rise, AlN/β-(In_0.21Ga_0.79)₂O₃ HEMTs are found to be ∼5× superior in terms of current carrying and power handling capability compared to β-(Al_0.2Ga_0.8)₂O₃/Ga₂O₃ HEMTs.

DOI：

https://doi.org/10.1063/5.0281648