High-field Breakdown and Thermal Characterization of Indium Tin Oxide Transistors

TL;DR

This study investigates the thermal and electrical breakdown of ultrathin amorphous indium tin oxide transistors, revealing how substrate choice affects heat dissipation, device failure, and potential for improved high-power applications.

Contribution

It combines experimental thermal microscopy with simulations to quantify thermal boundary conductance and failure mechanisms in ITO transistors on different substrates.

Findings

Breakdown temperatures are ~180°C on SiO2 and ~340°C on HfO2.

Thermal boundary conductance is estimated at 35 and 51 MW/m²K for SiO2 and HfO2, respectively.

HfO2 substrates enable higher breakdown power due to better heat dissipation.

Abstract

Amorphous oxide semiconductors are gaining interest for logic and memory transistors compatible with low-temperature fabrication. However, their low thermal conductivity and heterogeneous interfaces suggest that their performance may be severely limited by self-heating, especially at higher power and device densities. Here, we investigate the high-field breakdown of ultrathin (~4 nm) amorphous indium tin oxide (ITO) transistors with scanning thermal microscopy (SThM) and multiphysics simulations. The ITO devices break irreversibly at channel temperatures of ~180 {\deg}C and ~340 {\deg}C on SiO${_2}$ and HfO${_2}$ substrates, respectively, with failure primarily caused by thermally-induced compressive strain near the device contacts. Combining SThM measurements with simulations allows us to estimate a thermal boundary conductance (TBC) of 35 ${\pm}$ 12 MWm${^-}$${^2}$K${^-}$${^1}$ for ITO on SiO${_2}$, and 51 ${\pm}$ 14 MWm${^-}$${^2}$K${^-}$${^1}$ for ITO on HfO${_2}$. The latter also enables significantly higher breakdown power due to better heat dissipation and closer thermal expansion matching. These findings provide insights into the thermo-mechanical limitations of indium-based amorphous oxide transistors, which are important for more reliable and high-performance logic and memory applications.