We have used tetracyanoquinodimethane (TCNQ) as the active semiconduct
ing material in metal-insulator-semiconductor field-effect transistors
(MISFETs). TCNQ behaves as an n-type semiconductor. Differential capa
citance measurements on metal-insulator-semiconductor (MIS) devices co
nfirm the n-type behaviour. A maximum field-effect mobility of 3 x 10(
-5) cm2 V-1 s-1 is observed. On exposure to air the on/off ratio of th
e FETs improves to in excess of 450, due to oxidative dedoping of the
TCNQ and narrowing of the channel.