ATOMIC-SCALE IMPERFECTIONS AND FLUCTUATIONS IN THE TRANSMISSION PROPERTIES OF A QUANTUM-DOT

We examine the effects of atomic-scale imperfections on the transmissi on properties of a quantum dot resonant tunneling structure. For this purpose, we employ a three-dimensional model of quantum transport. We find that variation in the surface roughness of quantum dots leads to substantial fluctuations in the transmission properties. Impurities in a quantum dot are studied as a function of impurity strength and loca tion, and it is found that an attractive impurity near the center of a dot can reduce fluctuations caused by surface roughness. Nevertheless , the presence of more than a single impurity can give rise to a compl ex resonance structure that varies substantially with impurity configu ration.