A Poisson–Nernst–Planck Model of Ion Transport and Interface Segregation in Metal–Insulator–Semiconductor Structures and Solar Cells

Abstract

The presence of trace alkali ions, especially sodium (Na þ ), in semiconductor devices has long been identified as a cause of device instability due to ion-drift-induced voltage screening under operating temperatures and applied potentials. [1][2][3][4][5] In the last decade, it has been established that sodium contamination in silicon photovoltaic (PV) modules leads to a catastrophic power loss known as potential-induced degradation (PID), [6][7][8][9] which can lead to failure within a timescale of a few hours to several days under accelerated testing. [10][11][12][13][14][15] A critical component of PID is the transport of Na ions across the dielectric-Si interface, ultimately leading to shunting of the p-n junction. In contrast, the possibility of harnessing ion transport in dielectrics has attracted increasing interest for applications in neuromorphic computing. [16][17][18] Establishing rigorous models for these ion transport phenomena is a necessary step toward comprehensive control of mobile ions in established and novel semiconductor device architectures.Historically, electrostatic models of mobile charges in metal-insulatorsemiconductor (MIS) structures have had some success in reproducing phenomenological effects. [4,[19][20][21] Among these models, Snow et al. [19] proposed an analytical approximation to ion transport in MIS structures, which adequately describes electrostatic measurements of the image