EPITAXIAL AND DIFFUSIVE P-N GAAS JUNCTION WITH MICRORELIEF ACTIVE INTERFACE

摘要

This paper is aimed at elaboration of the technology of a submicron p~+-GaAs layer formation on microanotextured n-GaAs substrate by low temperature diffusion of zinc and characterization of corresponding solar cells with improved efficiency. To characterize the diffusive or epitaxial p~+-layers were measured: i) infrared reflectance spectra in the wave number range 200-5000 cm~(-1); ii) visible reflectance spectra (specular, diffuse); iii) atomic force microscope (AFM) images. Besides, external quantum efficiency spectra, dark and light I-V characteristics, C-V characteristics have been measured. As a result, the highest short-circuit current density values were obtained for structures with dendrite-like surface microrelief, in accordance with their optical properties, but the open-circuit voltage (V_(oc)) (and efficiency) values were the highest for the structures with quasigrating-like microrelief. Different diffusion conditions were shown to be optimal for structures with different microrelief morphology. To explain less value of V_(oc) for the structures with more developed microrelief the fluctuation model for the average V_(oc) was elaborated taking into account lateral fluctuation of doping impurity concentration and different components of the current flow.