A quantitative theoretical model for 1/fand low‐frequency noise due to bulk traps in semiconductor resistors has been developed. The model is based on the fact that random fluctuations of the steady‐state deep‐level‐trapped electron density, at some point in a depletion layer, decay exponentially with a relaxation time which depends on the local free electron density, the intrinsic properties of the semiconductor and the trap energy. The model, which is valid for relaxation times which are much longer than the free electron transit time, was applied to the case of a Schottky‐barrier field effect resistor. Our results show that the low‐frequency noise spectrum generated by deep‐level traps with a broad spatial distribution throughout the depletion layer, is very sensitive to Fermi‐Dirac trap statistics. The discrete distribution of flatband trap energy levels is the crucial parameter which determines the spectral density and range of the low‐frequency noise. Monoenergetic traps generate a considerably broadened Lorentzianlike low‐frequency noise spectrum which is highly sensitive to temperature. Traps with an arbitrary distribution over a set of discrete energy levels may exhibit 1/f noise or generic low‐frequency noise. We deduce the condition that has to be satisfied in order for an arbitrary discrete distribution of bulk traps over energy to exhibit 1/fnoise and derive an exact integral and approximate analytical expressions for the spectral density and range of bulk 1/f noise in semiconductors. The temperature dependence of the 1/fnoise spectrum is discussed while in the process elucidating the subtle temperature‐dependent relationship between 1/fand low‐frequency noise arising from bulk traps. Experimentally observed low‐frequency and 1/f noise characteristics are explicitly accounted for by the model. A qualitative argument for the application of the model to 1/fnoise generated by surface traps is given.
展开▼
