Atomic layer deposition (ALD) processes for forming Te-containing thin films, such as SbTe, GeTe, GeSbTe, BiTe, and ZnTe thin films are provided. ALD processes are also provided for forming Se-containing thin films, such as SbSe, GeSe, GeSbSe, BiSe, and ZnSe thin films are also provided. Te and Se precursors of the formula (Te,Se)(SiR.sup.1R.sup.2R.sup.3).sub.2 are preferably used, wherein R.sup.1, R.sup.2, and R.sup.3 are alkyl groups. Methods are also provided for synthesizing these Te and Se precursors. Methods are also provided for using the Te and Se thin films in phase change memory devices.

A photovoltaic device is presented. The photovoltaic device includes a layer stack; and an absorber layer is disposed on the layer stack. The absorber layer comprises selenium, wherein an atomic concentration of selenium varies across a thickness of the absorber layer. The photovoltaic device is substantially free of a cadmium sulfide layer.

Atomic layer deposition (ALD) processes for forming Te-containing thin films, such as SbTe, GeTe, GeSbTe, BiTe, and ZnTe thin films are provided. ALD processes are also provided for forming Se-containing thin films, such as SbSe, GeSe, GeSbSe, BiSe, and ZnSe thin films are also provided. Te and Se precursors of the formula (Te,Se)(SiR.sup.1R.sup.2R.sup.3).sub.2 are preferably used, wherein R.sup.1, R.sup.2, and R.sup.3 are alkyl groups. Methods are also provided for synthesizing these Te and Se precursors. Methods are also provided for using the Te and Se thin films in phase change memory devices.

Methods for growing and using large-grain templates are provided. According to an aspect of the invention, a method includes depositing a small-grain layer of a semiconductor material; treating the small-grain layer such that the small-grain layer becomes a large-grain layer; and growing an epitaxial layer of the semiconductor material on the large-grain layer. A ratio of an average grain size of the small-grain layer to a thickness of the small-grain layer is less than 1.0, and a ratio of an average grain size of the large-grain layer to a thickness of the large-grain layer is greater than 1.5.

Disclosed is a formulation of semiconductor nanoplatelets, including at least one nanoplatelet including a nanoplatelet core and a shell on the surface of the nanoplatelet core, wherein the formulation is substantially free of molecular oxygen and/or molecular water, and uses thereof.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

An improved feeder system and method for continuous vapor transport deposition that includes at least two vaporizers couple to a common distributor through an improved seal for separately vaporizing and collecting at least any two vaporizable materials for deposition as a material layer on a substrate. Multiple vaporizer provide redundancy and allow for continuous deposition during vaporizer maintenance and repair.

A semiconductor material emitting device is positioned such that its output flux impinges on a substrate at a non-perpendicular angle, so as to grow a first epilayer which is linearly graded in the direction perpendicular to the growth direction. The linear grading can be arranged such that, for example, each row of pixels has a different cutoff wavelength, thereby making it possible to provide a spectroscopic FPA without the use of filters. The non-perpendicular angle and/or the flux intensity can be adjusted to achieve a desired compositional grading. A spectral ellipsometer may be used to monitor the composition of the epilayer during the fabrication process, and to control the intensity of the flux.

A nanowire structure includes successive crystalline nanowire segments formed over a semiconductor substrate. A first crystalline segment formed directly on the semiconductor substrate provides electrical isolation between the substrate and the second crystalline segment. Second and fourth crystalline segments are each formed from a p-type or an n-type semiconductor material, while the third crystalline segment is formed from a semiconductor material that is oppositely doped with respect to the second and fourth crystalline segments.

A method for assembling semiconductor nanocrystals including: providing a binary system including semiconductor nanocrystals with an effective particle diameter of at most 20 nm, a first and a second solvent, the system having: a Ta, which is the temperature at which aggregation starts, a Ts, which is the solvent separation temperature of the system, an aggregation temperature range between Ta and Ts with Ta being included and Ts not, a homogeneous temperature range which is below Ta when Ta is lower than Ts and which is above Ta when Ta is higher than Ts, a heterogeneous temperature range which is above Ts when Ta is lower than Ts and below Ts when Ta is higher than Ts, and, bringing the temperature of the binary system from a value in the homogeneous temperature range to a value in the aggregation temperature range, thereby causing formation of an aggregate of the nanocrystals.