PROJECT

AlN/Oxide heterostructures for polarization enhanced transistors

The growing need for electricity, linked to the challenges of the digital and ecological transition, is boosting the power electronics market. Wide bandgap materials (GaN, SiC) allow pushing back the limits of silicon, while offering greater energy efficiency

However, ultra-wide-bandgap semiconductors have more promising properties than GaN or SiC for the next generation of power electronics. Among them, Ga₂O₃ presents a growing international interest because it meets the double challenge of reducing energy losses and lowering production costs.

Transistors incorporating a high-density two-dimensional electron gas (2DEG) channel are expected to be advantageous for increasing electron mobility thanks to the screening of the polar optical phonon and longitudinal optical phonon-plasmon coupling modes. The ALOFET project proposes an innovative, still unexplored approach, inspired by AlGaN/GaN high electron mobility transistors, which involves inducing the 2DEG by the polarization difference between an AlN barrier layer and the β-Ga₂O₃ channel.

The optimization of the AlN/β-Ga₂O₃ transistor requires to address a number of material challenges, such as the nucleation of epitaxial AlN on β-Ga₂O₃, the polarity of the AlN layer, the eventual activation of thermal interdiffusion or the crystalline purity of the β-Ga₂O₃ channel. The project aims to demonstrate a power transistor based on an AlN/β-Ga₂O₃ heterostructure and containing a polarization-induced 2DEG with a density around 10¹³ cm^-2.