Diffusion can be found everywhere in nature (mixing two liquids, etc.) In the pictures below are shown at moment t = 0 and t = t1, two containers with different liquid materials. It can be observed the phenomena of diffusion at t1. The concentrations of the two components decrease gradually at t1, due to the diffusion. After a larger period of time, the concentration of both materials may be constant everywhere in the container (perfectly mixed).
Diffusion may take place at room temperature with fluids, but for solids (for doping materials in microelectronics), a higher temperature may be required, thus the wafer is heated.
Substrate preparation
