A Kinetic Monte Carlo model for material aging: Simulations of second phase formation at Au/Bi2Te3 junction in oxygen environments

Abstract

Electronic properties of semiconductor devices are sensitive to defects such as second phase precipitates, grain sizes, and voids. These defects can evolve over time especially under oxidation environments and it is therefore important to understand the resulting aging behavior in order for the reliable applications of devices. In this paper, we propose a kinetic Monte Carlo framework capable of simultaneous simulation of the evolution of second phases, precipitates, grain sizes, and voids in complicated systems involving many species including oxygen. This kinetic Monte Carlo model calculates the energy barriers of various events based directly on the experimental data. As a first step of our model implementation, we incorporate the second phase formation module in the parallel kinetic Monte Carlo codes SPPARKS. Selected aging simulations are performed to examine the formation of second phase precipitates at the eletroplated Au/Bi2Te3 interface under oxygen and oxygen-free environments, and the results are compared with the corresponding experiments.

Thermal Stability and Mechanical Response of Bi2Te3-Based Materials for Thermoelectric Applications

“…Recently, a kinetic Monte Carlo model has been developed to simulate the second phase formation at Au/Bi 2 Te 3 junction under ambient atmosphere. 49 The formation of Bi 2 O 3 , TeO 2 , and AuTe 2 occurred when the Au/Bi 2 Te 3 junction was exposed to oxygen (Figure 4a,b). This is primarily due to the reaction between Bi and oxygen, which results in the deviation from stoichiometry in Bi 2 Te 3 , causing excess Te to combine with Au.…”

“…Moreover, the aging phenomena of Bi 2 Te 3 -based materials have also attracted attention when exposed to ambient atmosphere or intermediate temperatures for a long time. Both theoretical and experimental studies have been carried out to investigate the aging effect on TE properties of Bi 2 Te 3 -based materials. − Au is often deposited as electrodes to connect Bi 2 Te 3 -based thin films. Recently, a kinetic Monte Carlo model has been developed to simulate the second phase formation at Au/Bi 2 Te 3 junction under ambient atmosphere .…”

“…Both theoretical and experimental studies have been carried out to investigate the aging effect on TE properties of Bi 2 Te 3 -based materials. − Au is often deposited as electrodes to connect Bi 2 Te 3 -based thin films. Recently, a kinetic Monte Carlo model has been developed to simulate the second phase formation at Au/Bi 2 Te 3 junction under ambient atmosphere . The formation of Bi 2 O 3 , TeO 2 , and AuTe 2 occurred when the Au/Bi 2 Te 3 junction was exposed to oxygen (Figure a,b).…”

“…The light and dark precipitates correspond to AuTe 2 and Bi 2 O 3 +TeO 2 , respectively. Adapted with permission . Copyright 2014, AIP Publishing.…”

On atomic mechanisms governing the oxidation of Bi2Te3

“…Hence, the oxidation controversy still lingers on. In addition, a kinetic Monte Carlo based thermodynamic model of Bi 2 Te 3 /Au interface implies that Bi 2 O 3 , TeO 2 and AuTe 2 form upon oxygen exposure [19], but only a macroscopic picture is thus available, providing no atomic elucidation of the underlying oxidation mechanisms. It also seems that oxidation of Bi 2 Te 3 is strongly influenced by doping/ alloying or interfacing with other phases [20,21].…”