Applicability of Shockley–Read–Hall Theory for Interface States

Bernhard Ruch,Markus Jech,Gregor Pobegen,Tibor Grasser

doi:10.1109/ted.2021.3049760

Bernhard Ruch, Markus Jech + Show 2 more

Open Access

https://doi.org/10.1109/ted.2021.3049760

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Journal: IEEE Transactions on Electron Devices	Publication Date: Jan 15, 2021
Citations: 25	License type: CC BY 4.0

Affiliation: TU Wien

Abstract

The Shockley-Read-Hall (SRH) model has been successfully used for decades to describe the dynamics of interface states. Interestingly, the SRH model neglects structural relaxation at the defect site, which has a dramatic effect on the dynamics of oxide defects. One may, therefore, wonder why this omission has not led to serious and obvious discrepancies with experimental data. Using ab initio approaches to investigate Si dangling bonds, known as P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> centers, within a realistic Si/a-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> environment together with the more complete nonradiative multiphonon (NMP) theory, we explore why the SRH model provides an excellent approximation for interface traps but not for bulk oxide defects. We will also show that the commonly used Arrhenius correction of the capture cross section can be used to introduce a modified SRH model, which provides a reasonable approximation to the results obtained from a full NMP approach. However, it is shown that this Arrhenius correction may lead to incorrect relaxation energy estimations, especially for bulk oxide defects.

Highlights

T HE Shockley–Read–Hall (SRH) theory [1] is one of the most popular models for the transition dynamics between channel carriers and defects [2]–[4]
If we take the more complete nonradiative multiphonon (NMP) model as the benchmark, the SRH model performs worse than the SRH model with temperature compensation (SRHT) model, which is not surprising given that the SRHT model considers the relaxation energy in the capture cross section
Capture and emission time dependencies of the Fermi level can be compared for the three models (NMP, SRH, and SRHT) where the emission rates are constant over the Fermi level as they are independent of the carrier concentration

Summary

INTRODUCTION

T HE Shockley–Read–Hall (SRH) theory [1] is one of the most popular models for the transition dynamics between channel carriers and defects [2]–[4]. It does not consider the structural change of the defects upon changes of its charge state. It takes a relaxation energy due to structural reconfigurations of the involved defects into account. By investigating defects with larger relaxation energies, which are typically observed in bulk oxide defects, i.e., border traps, the limits of SRH models are demonstrated

MICROSCOPIC SIMULATION OF INTERFACE DEFECTS

ANALYTICAL TRAP MODELS

EXPERIMENTAL STRUCTURES AND MEASUREMENT PROCEDURE

RESULTS AND DISCUSSION

CONCLUSION