1/ƒ noise in diffused and ion-implanted MOS capacitors

Noise measurements in p-type diffused and ion-implanted MOS capacitors were conducted. It was found that there are three sources of $\text{1/?}$ noise: (1) number fluctuation $\text{1/?}$ noise. It is due to the interaction of holes with the surface oxide. (2) Bulk mobility fluctuation $\text{1/?}$ noise. It is due to the fluctuation in the bulk mobility. (3) Modulation $\text{1/?}$ noise. When inversion becomes important electrons in the inversion layer begin to interact with oxide traps. This gives rise to fluctuations in the surface potential, which in turn gives a $\text{1/?}$ modulation of the surface mobility or a direct modulation of the bulk resistance. The above experiment proves in a unique way that the two existing (1) and (2) models for the MOSFET can be observed simultaneously and lead to a surface potential fluctuating in a $\text{1/?}$ fashion.