LOW-FREQUENCY NOISE IN QUANTUM POINT CONTRACTS

The kinetics of electron transport in quantum point contacts has been studied by means of low-frequency noise spectroscopy. The temperature and frequency (Lorentzian or 1/f) dependences of the noise intensity a re found to be device specific, in contrast to the conductance depende nce, which universally exhibits a strong quantum size effect at low te mperatures. The origin of the Lorentzian noise spectrum is electron tr apping and release at a single trap close to the point contact, and is connected to random resistance switching in the time domain. The 1/f noise in other point contacts is attributed to a collection of traps i n the vicinity of the point contact. A comprehensive model is presente d which accounts for the conductance and temperature dependences of th e noise in quantum point contacts.