The present invention proposes a method to form a CdSeTe thin film with a defined amount of selenium and with a high quality. The method comprises the steps of providing a base substrate and of depositing a partial CdSeTe layer on a first portion of the base substrate. The step of depositing a partial CdSeTe layer is performed at least twice, wherein a predetermined time period without deposition of a partial CdSeTe layer on the first portion of the base substrate is provided between two subsequent steps of depositing a partial CdSeTe layer. The temperature of the base substrate and the CdSeTe layer already deposited on the first portion of the base substrate is controlled during the predetermined time period such that re-evaporation of Cd and/or Te from the CdSeTe layer already deposited takes place.

According to the embodiments provided herein, a photovoltaic device can include an absorber layer. The absorber layer can be doped p-type with a Group V dopant and can have a carrier concentration of the Group V dopant greater than 4×10.sup.15 cm.sup.−3. The absorber layer can include oxygen in a central region of the absorber layer. The absorber layer can include an alkali metal in the central region of the absorber layer. Methods for carrier activation can include exposing an absorber layer to an annealing compound in a reducing environment. The annealing compound can include cadmium chloride and an alkali metal chloride.

Mercury cadmium telluride (MCT) dual band photodiode elements are described that include an n-type barrier region interposed between first and second p-type regions. The first p-type region is arranged to absorb different IR wavelengths to the second p-type region in order that the photodiode element can sense two IR bands. A portion of the second p-type region is type converted using ion-beam milling to produce a n-type region that interfaces with the second p-type region and the n-type barrier region.

A monolithically integrated, tunable infrared pixel comprises a combined broadband detector and graphene-enabled tunable metasurface filter that operate as a single solid-state device with no moving parts. Functionally, tunability results from the plasmonic properties of graphene that are acutely dependent upon the carrier concentration within the infrared. Voltage induced changes in graphene's carrier concentration can be leveraged to change the metasurface filter's transmission thereby altering the “colors” of light reaching the broadband detector and hence its spectral responsivity. The invention enables spectrally agile infrared detection with independent pixel-to-pixel spectral tunability.

In one aspect, a method includes forming an electrical path between p-type mercury cadmium telluride and a metal layer. The forming of the electrical path includes depositing a layer of polycrystalline p-type silicon directly on to the p-type mercury cadmium telluride and forming the metal layer on the layer of polycrystalline p-type silicon. In another aspect, an apparatus includes an electrical path. The electrical path includes a p-type mercury cadmium telluride layer, a polycrystalline p-type silicon layer in direct contact with the p-type mercury cadmium telluride layer, a metal silicide in direct contact with the polycrystalline p-type silicon layer, and an electrically conductive metal on the metal silicide. In operation, holes, indicative of electrical current on the electrical path, flow from the p-type mercury cadmium telluride layer to the electrically conductive metal.

A photon avalanche diode, includes a quartz substrate, a doped HgCdTe contact layer on the substrate, an absorbing HgCdTe layer on the contact layer, a larger bandgap HgCdTe layer on the absorbing layer, a doped HgCdTe layer for a top contact layer on the larger bandgap HgCdTe layer, and a non-absorbing HgCdTe metasurface on the top contact layer.

Photo-detection device (100) including a semiconductor substrate (110) made of Cd.sub.xHg.sub.1-xTe, with an N-doped region (120), a P-doped region (130), and a concentrated casing (150) only located in the P-doped region and having an average cadmium concentration greater than the average cadmium concentration in the N-doped region. According to the invention, the concentrated casing (150) has a cadmium concentration gradient, defining therein at least one intermediate gap zone (151) and at least one high gap zone (152), and the intermediate gap zone (151) is in direct physical contact with an electrical contact block (170). A significant reduction in the dark current and an optimal charge carrier collection are thus combined.

The present disclosure relates to thin-film solar cells with improved efficiency and methods for producing thin-film solar cells having increased efficiency. In certain embodiments, thin-film solar cells having an efficiency of over 21%, over 20%, over 19%, over 15%, over 10%, etc. has been obtained using the methods of the disclosure. In certain aspects, the methods of the disclosure use passivation, passivating oxides, and/or doping treatments in increase the efficiency of the thin-film solar cells; e.g., CdTe-based thin-film solar cells.

The invention relates to methods for preparing 3-element semiconductor nanocrystals of the formula WYxZ(1-x), wherein W is a Group II element, Y and Z are different Group VI elements, and 0<X<1, comprising dissolving a Group II element, a first Group VI element, and a second Group VI element in a one or more solvents. The Group II, VI and VI elements are combined to provide a II:VI:VI SCN precursor solution, which is heated to a temperature sufficient to produce semiconductor nanocrystals of the formula WYxZ(1-x). The solvent used to dissolve the Group II element comprises octadecene and a fatty acid. The solvent used to dissolve the Group VI elements comprises octadecene. The invention also includes semiconductor nanocrystals prepared according to the disclosed methods, as well as methods of using the semiconductor nanocrystals.

In an example, a wireless gamma and or hard X-ray radiation detector includes a bulk semiconductor crystal, electrical contacts, a bias circuit, and a terahertz (THz) electromagnetic (EM) wave receiver. The bulk semiconductor crystal and includes indium antimonide (InSb), cadmium telluride (CdTe), or cadmium zinc telluride (CdZnTe). The electrical contacts are coupled to two facets of the bulk semiconductor crystal. The bias circuit is electrically coupled to the bulk semiconductor crystal through the electrical contacts. The THz EM wave receiver is positioned to detect THz radiation emitted by the bulk semiconductor crystal.