1/f noise in homogeneous and inhomogeneous media

Some experimental techniques for low-frequency resistance noise measurements are discussed. The criterion for using a low-noise current amplifier instead of voltage amplifier is given. A distinction is made between contact and bulk resistance contributions to the observed 1/f noise. The merits and difficulties of the application of the empirical relation for the 1/f noise in homogeneous and inhomogeneous media are addressed. The criterion that 1/f noise in homogeneous samples can only be detected for a number of free carriers N < 10(14) is calculated. The authors explain why the enhanced 1/f noise, due to poor crystal quality, current crowding at contacts or at grain boundaries, and at inhomogeneous internal interfaces can be used as a diagnostic tool for quality and reliability assessment of electronic devices.