We demonstrate a highly anisotropic conductivity, with a 10(9) ratio, betwe
en the in-plane and perpendicular electrical transport in organic insulator
/semiconductor heterostructures of monolayer thickness. These heterostructu
res are self-assembled monolayers made of alkyl chains and functionalized b
y various conjugated moieties at their ends. The high anisotropic conductiv
ity is due to the close packing of the conjugated end groups. These structu
res might be the building blocks of molecular-scale devices. (C) 2000 Ameri
can Institute of Physics. [S0003-6951(00)01810-6].