3. Charge Carrier Management (Thermal Noise Engineering)

This chapter considers nonequilibrium methods for thermal noise management. They include manipulation with charge carrier concentration within the detectors utilizing external fields and are implemented using micro and nanosystem techniques. The goal of nonequilibrium methods is to cause controlled perturbation of carrier distribution within the detector and thus locally decrease the carrier concentration below its equilibrium value, thereby directly decreasing the level of total generation-recombination noise. A classification of nonequilibrium methods is proposed, showing that in addition to the methods published in the literature one could utilize some new ones. A general mathematical model is presented that can be utilized in simulation of any nonequilibrium detector, including the novel ones. The model is derived for isothermal processes, but can be extended to nonisothermal structures. The main approaches analyzed herein include the contact phenomena, implemented by structures utilizing a combination of a built-in dopant concentration gradient and the external electric field for suppression of Auger processes. Two main types are considered, exclusion-based photoconductors and extraction-based photodiodes. Another approach for the suppression of Auger processes is the use of crossed electric and magnetic field, i.e. galvanomagnetic phenomena – the magnetoconcentration effect.