Effect of surface roughness on the properties of ohmic contacts to GaAs

Au/Ge/TiB_x/Au ohmic contacts to n-GaAs with textured surface have been developed and investigated. Two types of microrelief morphology (quasi-grating and dendrite-like), that are perspective for Solar Cell and sensor application, have been obtained by wet chemical anisotropic etching. The surface morphology and structural perfection were studied by AFM technique and x-ray diffractometry measurements. The effect of surface roughness on the value of contact resistivity and its lateral distribution has been investigated. The qualitative model for nonuniformity of ohmic contact formation caused by the dependence of intrinsic stresses on the interface roughness has been drawn to explain experimentally observed spread of electrical parameters.