Epitaxial growth of CZT(S,Se) on silicon

A method of forming an epitaxial kesterite-based photovoltaic device, comprising the steps of:

• selecting a Si substrate based on a crystallographic orientation of the Si substrate;
• forming an epitaxial kesterite material on the Si substrate which serves as an absorber layer of the photovoltaic device, wherein the epitaxial kesterite material comprises Cu, Zn, Sn, and at least one of S and Se, and wherein a crystallographic orientation of the epitaxial kesterite material is based on the crystallographic orientation of the Si substrate such that the crystallographic orientation of the epitaxial kesterite material is controlled by selecting the Si substrate having a particular crystallographic orientation;
• forming a buffer layer on a side of the epitaxial kesterite material opposite the Si substrate;
• and
• forming a transparent front contact on a side of the buffer layer opposite the epitaxial kesterite material.

An epitaxial kesterite-based device, comprising:

• a Si substrate;
• an epitaxial oxide interlayer on the Si substrate, wherein the epitaxial oxide interlayer comprises a material that is lattice-matched to Si;
• and
• an epitaxial kesterite material on a side of the epitaxial oxide interlayer opposite the Si substrate, wherein the epitaxial oxide interlayer serves to enhance wettability of the epitaxial kesterite material on the Si substrate, wherein the epitaxial kesterite material comprises Cu, Zn, Sn, and at least one of S and Se, wherein a crystallographic orientation of the epitaxial kesterite material is based on the crystallographic orientation of the Si substrate, and wherein the epitaxial oxide interlayer completely covers a surface of the Si substrate onto which the epitaxial kesterite material is formed and serves to prevent etching of the Si substrate.