A photodetector comprising a doped semiconductor photoabsorber, a barrier layer in contact with the photo absorber layer on one side, and at least one doped semiconductor contact area on the opposite side of the barrier layer. The barrier has a valence band energy substantially equal to the valence band energy of the photo absorber, and a thickness and a conductance band gap sufficient to allow tunneling of minority carriers, and block the flow of thermalized majority carriers from the photo absorber to the contact area. A P-doped or N-doped semiconductor may be utilized. The photoabsorber layer may extend past the one or more individual sections of the contact areas in the direction across the photo-detector.

Disclosed are a mercury cadmium telluride-black phosphorus van der Waals heterojunction infrared polarization detector and a preparation method thereof. The structure of the detector from bottom to top comprises a substrate, a mercury cadmium telluride material, an insulating layer, a two-dimensional semiconductor black phosphorus, and metal electrodes. First, growing the mercury cadmium telluride material on the substrate, removing part of the mercury cadmium telluride by ultraviolet lithography and argon ion etching, filling with aluminum oxide as the insulating layer using an electron beam evaporation method, transferring the two-dimensional semiconductor material black phosphorus at the junction of mercury cadmium telluride and an insulating layer assisted by a polypropylene carbonate film, and preparing the metal source-drain electrodes by electron beam lithography technology combined with the lift-off process to form the mercury cadmium telluride-black phosphorus van der Waals heterojunction infrared polarization detector.

Embodiments of a photovoltaic device are provided herein. The photovoltaic device can include a layer stack and an absorber layer disposed on the layer stack. The absorber layer can include a first region and a second region. Each of the first region of the absorber layer and the second region of the absorber layer can include a compound comprising cadmium, selenium, and tellurium. An atomic concentration of selenium can vary across the absorber layer. The first region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. The second region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. A ratio of an average atomic concentration of selenium in the first region of the absorber layer to an average atomic concentration of selenium in the second region of the absorber layer can be greater than 10.

Embodiments of a photovoltaic device are provided herein. The photovoltaic device can include a layer stack and an absorber layer disposed on the layer stack. The absorber layer can include a first region and a second region. Each of the first region of the absorber layer and the second region of the absorber layer can include a compound comprising cadmium, selenium, and tellurium. An atomic concentration of selenium can vary across the absorber layer. The first region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. The second region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. A ratio of an average atomic concentration of selenium in the first region of the absorber layer to an average atomic concentration of selenium in the second region of the absorber layer can be greater than 10.

A method for manufacturing a photodetection device, which includes the following steps: making a cadmium-rich structured coating, over a substrate of Cd.sub.xHg.sub.1-xTe, and using a first etching mask; etching to enlarge the through openings of the first etching mask or the through openings of an interlayer etched with the structured coating, so as to form a second etching mask; injecting acceptor doping elements into the substrate, throughout the second etching mask, and activating and diffusing the acceptor doping elements to form at least one P doped region in the semiconductor substrate; selective interdiffusion annealing of cadmium, so as to form in each P doped region a cadmium-rich concentrated well with a cadmium concentration lateral gradient; and making at least one electrical contact pad, at each through opening in the structured coating.

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 photovoltaic device includes a substrate structure and at least one Se-containing layer, such as a CdSeTe layer. A process for manufacturing the photovoltaic device includes forming the CdSeTe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process can also include controlling a thickness range of the Se-containing layer.

A photodetector comprising a doped semiconductor photoabsorber, a barrier layer in contact with the photo absorber layer on one side, and at least one doped semiconductor contact area on the opposite side of the barrier layer. The barrier has a valence band energy substantially equal to the valence band energy of the photo absorber, and a thickness and a conductance band gap sufficient to allow tunneling of minority carriers, and block the flow of thermalized majority carriers from the photo absorber to the contact area. A P-doped or N-doped semiconductor may be utilized. The photoabsorber layer may extend past the one or more individual sections of the contact areas in the direction across the photo-detector.

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.

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.