Silicon and germanium can have dreidl structures. Photograph by Tom Cerniglio. I n the past half century, the world has been transformed by an electronic revolution that is based largely on silicon technology. Semiconductor devices using this technology have become smaller and smaller, yet far more powerful, over time.
Defects have a profound effect on device performance.
In this country, only a few incongruously important groups like the air traffic controllers at O'Hare airport in Chicago have lagged this revolution and still use electronic equipment with vacuum tubes. Dislocations are line defects that are generally thought to be bad actors because among other things, they tend to suck in the dopants that make devices perform. The same negative view is held of planar defects like grain boundaries, which can be viewed as arrays of dislocations. In the worst case, if all the dopants so carefully introduced were to segregate to dislocations, the device would fail to work at all. Any electrical activity associated with dislocations was thought to be due to such impurity segregation or to the presence of so-called dangling bonds.