NOVELTY - The solar cell has solar subcell that is provided with an emitter layer (314), a base layer (322), and a window layer (336) adjacent to the emitter layer. The surface of the contact layer is passivated with sulfur. The contact layer is composed of Indium gallium arsenide. An upper first solar subcell is composed of a semiconductor material having a first band gap. The first solar subcell is provided with a base region and an emitter region. The window layer is mounted directly over the emitter region of upper first solar subcell and below the surface layer.    USE - Solar cells for space applications and terrestrial solar power applications.    ADVANTAGE - The subcell is provided with emitter layer, base layer, and window layer adjacent to emitter layer and surface of contact layer is passivated with sulfur, higher conversion efficiency of III-V compound semiconductor solar cells is achieved compared to silicon solar cells based on the ability to achieve spectral splitting of the incident radiation through the use of photovoltaic regions with different band gap energies, and accumulating the current from each of the regions. The window layer is introduced to improve subcell efficiency by preventing minority carrier recombination at the top surface of the emitter layer, hence the minority carriers present in the emitter is permitted to migrate to PN junction of the subcell, and contributing to the extracted electrical current. The window layer is provided with higher band gap than the adjacent emitter layer, the minority-carrier injection into the window layer can be suppressed, and thus the recombination of electron-hole pairs is reduced. The efficiency of photon conversion at that subcell is decreased, and the overall efficiency of the solar cell is increased. The process for the design and fabrication of window layer in multijunction solar cell improves light capture in the associated subcell and overall efficiency of the solar cell.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for manufacturing solar cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the solar cell of multijunction solar cell.    Middle subcell (307)    Top subcell (309)    Emitter layer (314)    Base layer (322)    Window layer (336)