1/f noise of GaAs resistors on semi-insulating substrates

A new theory is used to analyze the 1/f noise of GaAs resistors on semi-insulating substrates. It is demonstrated that this model can explain previously published results at moderately high frequencies for, in this example, resistive filaments on semi-insulating GaAs substrates. The model is based on a distributed equivalent circuit representation of the substrate, and shows that 1/f noise is a bulk phenomenon associated with the high resistivity substrates. The 1/f noise is not associated with number or mobility fluctuations in the channel, nor surface effects. One consequence of the theory is that in this particular instance Hooge's parameter is in reality no parameter, but is given by a simple formula which has a simple physical interpretation as the ratio of two charges: the thermal charge developed across the substrate capacitance and the charge associated with ionized donors in the resistor channel.