Correlation of 1/f Noise between Semiconductor Point Contacts with a Common Lead

We investigate cross spectral density between tunneling currents through closely spaced point contacts (PCs) in a semiconductor heterostructure. Analysis of 1/f noise, which originates from background charge fluctuations, is expected to reveal the characteristics of a charge detector and screened Coulomb potential in the device. However, the common resistance in the measurement circuit and the leads of the PCs causes a significant negative correlation. We find that this negative correlation is enhanced when the common electrical channel becomes so narrow that it has only a few one-dimensional conductive modes. Our finding suggests the importance of the circuit environment in integrating multiple charge detectors. (C) 2012 The Japan Society of Applied Physics