Low-frequency noise spectroscopy

Electrical noise in excess of thermal and shot noise is caused by imperfections in the device. Its control can improve the quality of the device and its measurement can give considerable information about the nature of the defects involved. For defects with discrete energy distributions spectroscopy can be used to identify the defect and measure its properties. Excess noise has large intensity at low frequencies and several mechanisms can be identified. The value of the technique for many systems is described. Comparison is made with other methods of studying such defects.< >