Development of Ge solar cells for multijunction solar cells, where the p-n junction is formed by ion implantation is investigated. Ge samples are doped by phosphorus (P) ions having 60 keV energy at dose ratios of 1x10(13), 1x10(14), 1x10(16) ve 1x10(16) ions/cm(2) at room temperature. The influences of P concentration and activation temperature on Ge solar cells is investigated. P concentration and layer resistance are measured by secondary ion mass spectrometry (SIMS) and a 4-point probe, respectively. Layer resistances of Ge samples are observed to vary as a function of concentration and temperature. The short circuit currents (I-sc) and open circuit voltages (V-oc) of the Ge solar cells is compared through examination of the I-V curves of the cells with respect to concentration and temperature. Besides, alpha-Si thin films are introduced as anti-reflection coatings (ARCs) via DC sputtering method and the impact of ARCs on I-sc and V-oc is investigated. The ARCs is observed to increase the I-sc's of all four samples with respect to uncoated samples.