A University of California, Berkeley, researcher has developed a way to apply semiconductor dopants at the atomic level. Controlling the amount of dopant applied is increasingly important as the size of wires, diodes, transistors, switches, and other semiconductor elements approaches molecular scale. During semiconductor fabrication, manufacturers typically add dopants to semiconductor materials, such as silicon, to change their performance by altering their electrical properties. P-type doping adds elements such as boron or indium to remove electrons. N-type doping inserts elements such as arsenic, phosphorous, or potassium to add electrons. Currently, chip makers frequently add dopants in bulk to semiconductor materials. However, as the elements become smaller, the amount and placement of doping must become more precise.