A semiconductor film includes a two-dimensional (2D) material layer having a hexagonal in-plane lattice structure, and a substantially planar Group IV semiconductor layer having a direct band gap on the 2D material layer. A method of fabricating a semiconductor material includes growing a Group IV semiconductor material on a two-dimensional material having a hexagonal in-plane lattice structure. This growth process results in the Group IV semiconductor material having a direct band gap. The semiconductor films may be used in any optoelectronic device, including flexible devices.

The solar cell includes a substrate, a tunneling layer disposed on a first surface, and a first doped conductive layer disposed on a surface of the tunneling layer. The solar cell further includes a second doped conductive layer disposed on a surface of the first doped conductive layer, where the second doped conductive layer includes: multiple first portions and multiple second portions arranged alternately in a direction perpendicular to a predetermined direction and perpendicular to a thickness direction of the second doped conductive layer, each of the multiple first portions and the multiple second portions extends along the predetermined direction, a doping element concentration of the first doped conductive layer is lower than a doping element concentration of each of the multiple first portions, and the doping element concentration of each of the multiple first portions is lower than a doping element concentration of each of the multiple second portions.

A solar cell comprising a bulk germanium silicon growth substrate; a diffused photoactive junction in the germanium silicon substrate; and a sequence of subcells grown over the substrate, with the first grown subcell either being lattice matched or lattice mis-matched to the growth substrate.

A method for forming a photovoltaic device includes providing a substrate. A layer is deposited to form one or more layers of a photovoltaic stack on the substrate. The depositing of the amorphous layer includes performing a high power flash deposition for depositing a first portion of the layer. A low power deposition is performed for depositing a second portion of the layer.

A semiconductor device comprising a substrate having a region protruding from the substrate surface; a relaxed semiconductor disposed on the region; an additional semiconductor disposed on the relaxed semiconductor; and low density dielectric disposed next to and at least partially underneath the relaxed semiconductor and adjacent to the protruding region of the substrate.