A method for producing a substantially planar surface for semiconductor processing to improve lithography, planarization, and other process steps that benefit from a flat substrate. The method includes depositing a first alloy to form a first layer on a substrate. The first layer has a center high deposition, meaning the height in the center of the substrate is higher than the height at the edges of the substrate. The method further includes depositing a second alloy on the first layer to form a second layer. The first alloy has a different composition than the second alloy. In such a method the net deposition is substantially planar reducing or eliminating deposition induced long-range distortions that might occur across a substrate.

A method for producing a layer system for thin-film solar cells is described, wherein a) an absorber layer is produced, and b) a buffer layer is produced on the absorber layer, wherein the buffer layer contains sodium indium sulfide according to the formula Na.sub.xIn.sub.y-x/3S with 0.063≦x≦0.625 and 0.681≦y≦1.50, and wherein the buffer layer is produced, without deposition of indium sulfide, based on at least one sodium thioindate compound.

A laser structure includes a substrate and a first dielectric layer formed on the substrate. A multi-quantum well is formed on the first dielectric layer and has a plurality of alternating layers. The alternating layers include a dielectric layer having a sub-wavelength thickness and a monolayer of a two dimensional material.

A method of fabricating a buffer layer of a photovoltaic device comprises: providing a substrate having a back contact layer disposed above the substrate and an absorber layer disposed above the back contact layer; depositing a metal layer on the absorber layer; and performing a thermal treatment on the deposited metal layer in an atmosphere comprising sulfur, selenium or oxygen, to form a buffer layer.

A composition of matter comprising a film on a graphitic substrate, said film having been grown epitaxially on said substrate, wherein said film comprises at least one group III-V compound or at least one group II-VI compound.

Embodiments are presented herein that provide a TMD system wherein the first layered material is made of heterobilayers or multilayers with semiconducting direct band gaps. The first layered material may be made of multiple layers of different TMD with different stackings, exhibiting smaller direct and indirect band gaps smaller than monolayer systems of TMD.

A quantum well device includes a first layer of a first two-dimensional material, a second layer of a second two-dimensional material, and a third layer of a third two-dimensional material disposed between the first layer and second layer. The first layer, the second layer, and the third layer are adhered predominantly by van der Waals force.

A method to fabricate thin-film photovoltaic devices including a photovoltaic Cu(In,Ga)Se.sub.2 or equivalent ABC absorber layer, such as an ABC.sub.2 layer, deposited onto a back-contact layer characterized in that the method includes at least five deposition steps, during which the pair of third and fourth steps are sequentially repeatable, in the presence of at least one C element over one or more steps. In the first step at least one B element is deposited, followed in the second by deposition of A and B elements at a deposition rate ratio A.sub.r/B.sub.r, in the third at a ratio A.sub.r/B.sub.r lower than the previous, in the fourth at a ratio A.sub.r/B.sub.r higher than the previous, and in the fifth depositing only B elements to achieve a final ratio A/B of total deposited elements.

Methods of making molybdenum sulfide (MoS.sub.2) on a stretchable substrate are disclosed. The method includes magnetron sputtering MoS.sub.2 onto a stretchable substrate, such as a stretchable polymeric material, at low temperatures to form a film precursor, and illumination annealing the film precursor to form high quality MoS.sub.2. The illumination source may be a laser or other source of radiation. Also, two-dimensional nanoelectronic devices made by the methods and/or from the high quality MoS.sub.2 are disclosed.

A method for manufacturing a CZTS based thin film having a dual band gap slope, comprising the steps of: forming a Cu.sub.2ZnSnS.sub.4 thin film layer; forming a Cu.sub.2ZnSn(S,Se).sub.4 thin film layer; and forming a Cu.sub.2ZnSnS.sub.4 thin film layer. A method for manufacturing a CZTS based solar cell having a dual band gap slope according to another aspect of the present invention comprises the steps of: forming a back contact; and forming a CZTS based thin film layer on the back contact by the method described above.