Cryogenic field-effect transistor with single electronic charge sensitivity

Abstract
We have fabricated matched pairs of cryogenic field-effect transistors with input charge sensitivity qn=0.01 e/√Hz at T=1.3 K, low input capacitance 0.4 pF, and extremely high input resistance in excess of 1015 Ω. Low leakage permits dc charge-coupled operation for times up to ∼103 s. The channel noise is characterized by a flat spectrum at high frequencies, and 1/f noise below a corner frequency fc<1 kHz. These devices can resolve charge differences as small as qn√fc=0.4e.