Simulating and Modeling the Influence of Deep Trench Interface Recombination on Si Photodiodes

Abstract

Deep Trench Isolation (DTI) is a common termination technique in optoelectronics to minimize cross-talk between single devices fabricated on the same chip. However, DTI can also affect the performance of optoelectronic devices. In this work we simulate and model the influence of minority carrier recombination at the DTI interface on the quantum efficiency, i.e. responsivity, of Si photodetectors. We demonstrate that DTI interface recombination is a non-linear effect with respect to the applied irradiance and causes a non-linear response of the photodetector, which must be avoided for certain applications. Furthermore, we show that sufficiently high positive or negative fixed oxide charges can improve device performance by reducing the DTI interface recombination. To maintain the benefit of electrical cross-talk minimization in combination with an almost linear responsivity we propose a structure terminated with lateral deep trench metal oxide semiconductor capacitors (DTMOSCAPs) to control the passivation of the DTI interface by an applied gate bias. By means of TCAD simulations, we show that such a device is superior to default DTI structures in terms of responsivity as well as linearity.