CRYOGENIC FIELD-EFFECT TRANSISTOR WITH SINGLE ELECTRONIC CHARGE SENSITIVITY

We have fabricated matched pairs of cryogenic field-effect transistors with input charge sensitivity q(n)=0.01 e/root Hz at T = 1.3 K, low i nput capacitance 0.4 pF, and extremely high input resistance in excess of 10(15) Omega. Low leakage permits dc charge-coupled operation for times up to similar to 10(3) s. The channel noise is characterized by a flat spectrum at high frequencies, and 1/f noise below a corner freq uency f(c)<1 kHz. These devices can resolve charge differences as smal l as q(n) root f(c)=0.4e.