A concrete having a smooth surface, which is wholly or partly coated with a polymer film obtained by polymerisation under the action of radiation, where the film is itself wholly or partly coated with a thin photovoltaic film.

A vertical tunneling FET (TFET) provides low-power, high-speed switching performance for transistors having critical dimensions below 7 nm. The vertical TFET uses a gate-all-around (GAA) device architecture having a cylindrical structure that extends above the surface of a doped well formed in a silicon substrate. The cylindrical structure includes a lower drain region, a channel, and an upper source region, which are grown epitaxially from the doped well. The channel is made of intrinsic silicon, while the source and drain regions are doped in-situ. An annular gate surrounds the channel, capacitively controlling current flow through the channel from all sides. The source is electrically accessible via a front side contact, while the drain is accessed via a backside contact that provides low contact resistance and also serves as a heat sink. Reliability of vertical TFET integrated circuits is enhanced by coupling the vertical TFETs to electrostatic discharge (ESD) diodes.

Photovoltaic devices based on an Ag.sub.2ZnSn(S,Se).sub.4 (AZTSSe) absorber and techniques for formation thereof are provided. In one aspect, a method for forming a photovoltaic device includes the steps of: coating a substrate with a conductive layer; contacting the substrate with an Ag source, a Zn source, a Sn source, and at least one of a S source and a Se source under conditions sufficient to form an absorber layer on the conductive layer having Ag, Zn, Sn, and at least one of S and Se; and annealing the absorber layer. Methods of doping the AZTSSe are provided. A photovoltaic device is also provided.

A method is provided for fabricating a thin-film semiconductor device. The method includes providing a plurality of raw semiconductor materials. The raw semiconductor materials undergo a pre-reacting process to form a homogeneous compound semiconductor material. This pre-reaction typically includes processing above the liquidus temperature of the compound semiconductor. The compound semiconductor material is reduced to a particulate form and deposited onto a substrate to form a thin-film having a composition and atomic structure substantially the same as a composition and atomic structure of the compound semiconductor material.

A multi-junction photovoltaic cell includes a substrate and a back contact layer formed on the substrate. A low bandgap Group IB-IIIB-VIB.sub.2 material solar absorber layer is formed on the back contact layer. A heterojunction partner layer is formed on the low bandgap solar absorber layer, to help form the bottom cell junction, and the heterojunction partner layer includes at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter. The high resistivity material has the formula (Zn and/or Mg)(S, Se, O, and/or OH). A conductive interconnect layer is formed above the heterojunction partner layer, and at least one additional single-junction photovoltaic cell is formed on the conductive interconnect layer, as a top cell. The top cell may have an amorphous Silicon or p-type Cadmium Selenide solar absorber layer. Cadmium Selenide may be converted from n-type to p-type with a chloride doping process.

A method for producing a P-N junction in a thin film photovoltaic cell comprising a deposition step in which are carried out successively: a layer of precursors of a photovoltaic material of type P or N, a barrier layer and a layer of precursors of a semiconducting material of type N or P, this deposition step being followed by an annealing step carried out with a supply of S and/or Se, this annealing step leading to the formation of an absorbing layer of the type P or N and of a buffer layer of type N or P and of a P-N junction at the interface between said layers.

An optoelectronic device configured for improved light extraction through a region of the device other than the substrate is described. A group III nitride semiconductor layer of a first polarity is located on the substrate and an active region can be located on the group III nitride semiconductor layer. A group III nitride semiconductor layer of a second polarity, different from the first polarity, can located adjacent to the active region. A first contact can directly contact the group III nitride semiconductor layer of the first polarity and a second contact can directly contact the group III nitride semiconductor layer of the second polarity. Each of the first and second contacts can include a plurality of openings extending entirely there through and the first and second contacts can form a photonic crystal structure. Some or all of the group III nitride semiconductor layers can be located in nanostructures.

A heterostructure for use in an electronic or optoelectronic device is provided. The heterostructure includes one or more semiconductor layers containing columnar nanostructures (e.g., nanowires). The nanowire semiconductor layer can include sub-layers of varying composition, at least one of which is an active layer that can include quantum wells and barriers. A heterostructure can include n-type and p-type semiconductor contact layers adjacent to the nanowire semiconductor layer containing the active layer.

A photodetector includes an insulating layer on a substrate, a first graphene layer on the insulating layer, a 2-dimensional (2D) material layer on the first graphene layer, a second graphene layer on the 2D material layer, a first electrode on the first graphene layer, and a second electrode on the second graphene layer. The 2D material layer includes a barrier layer and a light absorption layer. The barrier layer has a larger bandgap than the light absorption layer.

Photovoltaic cells, photovoltaic devices, and methods of fabrication are provided. The photovoltaic cells include a transparent substrate to allow light to enter the photovoltaic cell through the substrate, and a light absorption layer associated with the substrate. The light absorption layer has opposite first and second surfaces, with the first surface being closer to the transparent substrate than the second surface. A passivation layer is disposed over the second surface of the light absorption layer, and a plurality of first discrete contacts and a plurality of second discrete contacts are provided within the passivation layer to facilitate electrical coupling to the light absorption layer. A first electrode and a second electrode are disposed over the passivation layer to contact the plurality of first discrete contacts and the plurality of second discrete contacts, respectively. The first and second electrodes include a photon-reflective material.