Electrical noise as a reliability indicator in electronic devices and components

Low-frequency electrical noise is well accepted as a very sensitive measure of the quality and reliability of electrical components and electronic devices. It shows changes in magnitude very much greater than in the static electrical properties. The excess noise is due to defects and nonideality in the device. Although the excess noise is a general indicator of quality there can be many physical processes that could be involved. These noise contributions are additive and therefore not easy to distinguish so that the noise is not so valuable as a diagnostic tool. Also, there is not a detailed understanding of some noise sources, such as in some semiconductor devices. Recently devices have continued to become smaller in size so that the noise signal has become more significant compared to the real signal and the number of individual defects involved has become fewer. This has resulted in a growing trend to the study of the time varying signal rather than the noise spectral density. A review is given of the developments in the subject over the last few years