Patent ID: 8957306
Filing Date: 2015-02-17
Classification: H01L,Y02E

Abstract:
1. A solar cell comprising: a first subcell including a bulk germanium (Ge) substrate composed entirely of doped or undoped germanium, the bulk Ge substrate having a diffusion region doped with n-type dopants including phosphorus and arsenic, wherein an upper portion of such diffusion region has a higher concentration of phosphorus (P) atoms than arsenic (As) atoms, wherein the diffusion region further includes a lower portion, and As atoms have a higher concentration compared to P atoms in the lower portion, a second subcell including a layer of either gallium arsenide (GaAs) or indium gallium arsenide (InGaAs) disposed over the bulk Ge substrate, a nucleation layer in direct physical contact with the bulk Ge substrate, wherein the nucleation layer controls the diffusion of As atoms into the substrate, the nucleation layer being devoid of arsenic.