Changing Conductive Properties by Diffusion (Middle and High School curriculum lesson)

In the semiconductor industry scientists take advantage of diffusion to "dope" or introduce atoms into a silicon wafer to change its conductive properties. The lesson simulates the diffusion of a gas phase substance (ammonia) into a solid substrate (gelatin) and compares the lab model of diffusion to the doping process of silicon wafers. Students will examine how diffusion occurs and explore how the electrical properties of semiconductors are developed. This lesson uses only commonly available substances.