BAND-TO-BAND ILLUMINATION IN NOISE SEMICONDUCTOR SPECTROSCOPY

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