Origin of 1/f noise in bipolar transistors

In planar n-p-n transistors fabricated in IC technology, the dependence of 1/ noise on the base current density jB, the base width WB, and the emitter area FEwas measured. The power spectrum of the base current fluctuations iBcan be represented by the empirical relation where and β has been found to be 1.3 or 2. The results of measurements on gate-controlled devices indicate that 1/ noise cannot be explained by McWhorter\´s surface model. Therefore, a new model is proposed which assumes resistance fluctuations in the base region as the cause of 1/ noise in bipolar transistors. The model establishes the relation for as well as the magnitude of the coefficients β and γ.