Point Defects and Diffusion in Semiconductors

Abstract

Semiconductor devices generally contain n- and p-doped regions. Doping is accomplished by incorporating certain impurity atoms that are substitutionally dissolved on lattice sites of the semiconductor crystal. In defect terminology, dopant atoms constitute extrinsic point defects. In this sense, the whole semiconductor industry is based on controlled introduction of specific point defects. This article addresses intrinsic point defects, ones that come from the native crystal. These defects govern the diffusion processes of dopants in semiconductors. Diffusion is the most basic process associated with the introduction of dopants into semiconductors. Since silicon and gallium arsenide are the most widely used semiconductors for microelectronic and optoelectronic device applications, this article will concentrate on these two materials and comment only briefly on other semiconductors.A main technological driving force for dealing with intrinsic point defects stems from the necessity to simulate dopant diffusion processes accurately. Intrinsic point defects also play a role in critical integrated circuit fabrication processes such as ion-implantation or surface oxidation. In these processes, as well as during crystal growth, intrinsic point defects may agglomerate and negatively impact the performance of electronic or photovoltaic devices. If properly controlled, point defects and their agglomerates may also be used to accomplish positive goals such as enhancing device performance or processing yield.