Solar cells and methods for manufacture thereof

Abstract

An improved light transducer such as a solar cell and, especially, a concentrator solar cell, together with processes for forming the same which permit the formation of improved light transducers characterized by their high thermal stability and by optimized impurity atom dispersion zones at the surface of either a p-type or an n-type substrate--such, for example, as a silicon substrate--defining: (i) a thermally stable deep junction with relatively high surface concentrations of dopant dispersed in those areas where metallic electrodes are to be formed, thus providing excellent ohmic contact characteristics in such areas; and (ii), an efficient energy conversion shallow junction with relatively lower surface concentrations of dopant in the inter-electrode photoactive regions of the cell, with such inter-electrode photoactive regions preferably being texturized, thereby optimizing current generation per unit of incident radiation and minimizing reflection losses. More particularly, a deep junction (on the order of 0.5 .mu.m or greater) is first formed throughout the substrate's entire near-surface area which is to be exposed to incident radiation; such deep junction is then entirely removed in the inter-electrode regions of the substrate by subjecting such regions to an acid etch, preferably with a texturizing etchant but, in some instances, with a polish etchant; and, a relatively uniform shallow junction (on the order of 0.3 .mu.m.+-.0.1 .mu.m) is then formed in the etched inter-electrode near-surface regions either (i) by subjection of the substrate to a gas diffusion dopant process, or (ii), by conventional ion implantation techniques.