For the fabrication of organic transistors sexithiophene (6T) is one o
f the most promising materials. Since high purity improves the transis
tor performance of 6T, the FET described here was built on an ultrapur
e sexithiophene single crystal, shown in the figure as a gray block. T
he characteristics of this transistor-better than those of FETs based
on evaporated polycrystalline sexithiophene-are presented.