MEASUREMENT OF THE DIFFUSION LENGTH OF MINORITY CHARGE-CARRIERS USINGREAL SCHOTTKY BARRIERS

The characteristic features of the held dependence of the short-circui t photocurrent of real Schottky barriers based on strongly doped semic onductors under conditions of an oscillatory dependence of the light a bsorption coefficient alpha on the field intensity in the space-charge region and the photon energy (h nu>E,) are analyzed. An analytical ex pression is obtained for the dependence of the photocurrent on the thi ckness W of the space-charge region when the condition alpha W much le ss than 1 is satisfied. An improved method is proposed for determining the diffusion length of minority charge carriers by analyzing the dep endence I-p(W) in the spectral region satisfying the conditions of app licability of the expressions obtained. Some improvements are also mad e in the method for distinguishing the capacitance of the space-charge region from the high-frequency capacitance of a real Schottky barrier . The method is tested on structures Au-GaAs with N-d=4.5 X 10(16)-1 X 10(18) cm(?)(-3). The method of determining L is checked independentl y on the basis of a theoretical description of the spectral dependence of the quantum efficiency of the structure. (C) 1997 American Institu te of Physics.