Identification of 1/F Noise Producing Mechanisms in Electronic Devices.

In recent years, theorists have been trying to explain the phenomenon of electrical 1/f noise. Presently some controversy exists over the exact origin of the fluctuating physical quantities which gives rise to these resistance fluctuations. The disputes have centered on fluctuations of carrier mobility, carrier number, and temperature, any of which could cause the observed resistance fluctuations. The primary thrust of our research is to determine which of these possible 1/f noise producing mechanisms is responsible for the 1/f noise commonly observed in two electronic devices (i.e. thin film resistors and PNP transistors). First, we delve into the details of two competing 1/f noise theories of metal thin films--Dutta and Horn's Number Fluctuations theory and Handel's Quantum 1/f Noise theory (i.e. mobility fluctuations). Then, we review the results of previous investigators in 1/f noise, in order to identify the areas needed to be researched. Our central experimental effort has been to devise methods to distinquish between the three possible 1/f noise producing mechanisms. We show a lack of correlation between the 1/f noises of two devices in the same thermal environment and conclude that temperature fluctuations do not produce the 1/f noise. We find two methods to discriminate between number and mobility fluctuations (i.e. changing of the source resistance for active devices and changing the ambient temperature in passive devices). Results from both the thin films and the transistors show for the observed current noise both number fluctuations and mobility fluctuations may be present, but under certain experimental conditions one mechanism will dominate. Finally, the application of Handel's Quantum theory to the noise observed in thin films at low temperatures leads us to believe that Quantum 1/f noise does exist and sets a theoretical minimum to all 1/f noise.