RESONANT-TUNNELING IN 2 DIMENSIONS VIA AN IMPURITY

We solve an exact model of two-dimensional resonant tunneling through a potential barrier with a point defect. The model shows that the scat tering amplitude has a very narrow spreading angle, and gets its maxim al value for a small incoming angle. Even when the incoming wave is a narrow beam of electrons, the transmission coefficient depends very st rongly on the position of the impurity. This characteristic can be use d to detect the position of an impurity (or defect) in a two-dimension al layer.