Band-to-band illumination in noise semiconductor spectroscopy

The effect of band-to-band illumination on noise spectra has been investigated in n-GaAs with an equilibrium concentration n(0) = 10(17) cm(-3). The theoretical predictions of Levinshtien et al have been compared in detail with experimental results. A new local level has been observed and investigated using the technique of level recharging by minority carriers. The capture cross section of this level depends exponentially on temperature: sigma = sigma(0) exp(-E(1)/kT). The level parameters: activation energy E(1), level energy E(0), capture cross section sigma and trap concentration N-1 have been determined. Using band-to-band illumination techniques the parameters of a trap investigated recently by Copland have been redetermined. It has been shown that band-to-band illumination is a very effective tool in noise spectroscopy.