Electrometry on charge traps with a single-electron transistor

Background charge fluctuators are studied individually by means of a modified single-electron pump. Operation of the device in a feedback mode allows electrometric sensing of the charged background and its behavior upon electric potential variations due to geometrically different gates. Pulse height spectra and hysteresis of charge trapping transitions are discussed as a specific signature of distinct fluctuators. The location of individual traps is determined from the experimental data and based on electrostatic calculations.