Analytical Frequency-Dependent Formulas of Excess Noise in Homogeneous Semiconductors

An analytic formula is presented for the excess noise current spectral density in homogeneous semiconductors, which originates from uniformly‐distributed diffusion noise sources inside the device. As the drift transit time becomes shorter than the dielectric relaxation time, the excess noise current power becomes larger than that of thermal noise and this excess noise behaves like full shot noise with larger electric field. This formula shows how the carrier transit time, the dielectric relaxation time, and the collision time play each role in determining the terminal noise current. As the excess noise approaches the full shot noise level, the power spectral density of the excess noise shows a peak around the angular frequency determined by the inverse of the collision time.