# Origin of Threshold Voltage Instabilities in Indium Oxide Transistors

## TL;DR

This paper explains how surface oxygen affects the reliability of indium oxide transistors and proposes a model to understand and improve their performance.

## Contribution

The study introduces a unified kinetic model to describe threshold voltage instabilities in indium oxide transistors caused by surface oxygen interactions.

## Key findings

- Threshold voltage drifts in In2O3 transistors are caused by interactions between surface-adsorbed oxygen and the channel.
- External factors like UV/X-ray, thermal annealing, and bias stress alter these interactions, leading to instability.
- Recovery dynamics of threshold voltage are consistent across different perturbations, suggesting a universal mechanism.

## Abstract

Oxide semiconductors
have gained substantial interest for their
low-temperature processability, allowing for their integration as
functional add-on device layers for advanced monolithic 3D integrated
circuits (ICs). However, reliability issues, particularly under thermal,
environmental, and electrical stresses, remain critical issues and
require immediate solutions. This study investigates the instability
of ultrathin In2O3 transistors, revealing that
threshold voltage (V
T) drifts arise from
interactions between surface-adsorbed oxygen and the In2O3 channels. We show that the oxygen in the ambient atmosphere
attached to the In2O3 surface plays a crucial
role in modulating In2O3 conductivity, thereby
governing V
T. External perturbations such
as ultraviolet (UV)/X-ray illumination, thermal annealing, and bias
stress could alter this interaction of surface oxygen with ultrathin
In2O3, leading to a V
T drift. Importantly, we propose a unified kinetic model that provides
a generic physical description of V
T instabilities
induced by these commonly observed factors. By characterizing time-dependent V
T instability, the model demonstrates that recovery
dynamics exhibit identical behavior across all tested perturbations,
indicating that the recovery process is independent of the initial
stimulus. This study uncovers the surface oxygen as a critical factor
affecting In2O3 transistor reliability, offering
insights for designing oxide-based devices for advanced electronic
and optoelectronic devices.