A 0.2-mm-thick wafer of silicon is treated so that a uniform concentration gradient of antimony is produced.

Question:

A 0.2-mm-thick wafer of silicon is treated so that a uniform concentration gradient of antimony is produced. One surface contains 1 Sb atom per 108 Si atoms and the other surface contains 500 Sb atoms per 108 Si atoms. The lattice parameter for Si is 5.4307 Å (Appendix A). Calculate the concentration gradient in
(a) Atomic percent Sb per cm; and
(b) Sb atoms/(cm3 · cm).