A solar cell stack includes a first semiconductor solar cell having a p-n junction made of a first material with a first lattice constant, a second semiconductor solar cell having a p-n junction made of a second material with a second lattice constant, and the first lattice constant being at least 0.008 Å smaller than the second lattice constant, and a metamorphic buffer. The metamorphic buffer is formed between the first semiconductor solar cell and the second semiconductor solar cell. The metamorphic buffer includes a series of at least five layers. The lattice constant increases in the series in the direction of the semiconductor solar cell. The lattice constants of the layers of the metamorphic buffer are larger than the first lattice constant. Two layers of the buffer having a doping and the difference in the dopant concentration between the two layers being greater than 4E.sup.17 cm.sup.−3.

A solar cell stack, having a first semiconductor solar cell having a p-n junction made of a first material with a first lattice constant, and a second semiconductor solar cell having a p-n junction made of a second material with a second lattice constant, and the first lattice constant being at least 0.008 Å smaller than the second lattice constant, and a metamorphic buffer, the metamorphic buffer being formed between the first semiconductor solar cell and the second semiconductor solar cell, and the metamorphic buffer including a series of three layers, and the lattice constant increasing in a series in the direction of the semiconductor solar cell, and the lattice constants of the layers of the metamorphic buffer being bigger than the first lattice constant, two layers of the buffer having a doping, and the difference in the dopant concentration between the two layers being greater than 4E17 cm.sup.−3.

A semiconductor light-receiving element (50) is a semiconductor light-receiving element in which a multi-plication layer (2), an electric-field control layer (3), a light absorption layer (4) and a window layer (5) are sequentially formed on a semiconductor substrate (1), and a p-type region (6) is formed in the window layer (5). The p-type region (6) has a first p-type portion (14) and a second p-type portion (15) whose current multiplication factor due to light incidence is larger than that of the first p-type portion (14). The first p-type portion (14) is formed as a central portion of the p-type region (6), the central portion including a central axis (21c) perpendicular to the semiconductor substrate (1), and the second p-type portion (15) is formed on an outer periphery of the central portion in a radial direction about the central axis (21c).

An avalanche photodiode with a diffused junction and the method for its fabrication are disclosed. The method comprising forming, on a substrate, a first high-doped region and a low-doped region; performing selective area growth (SAG) with in-situ etchant on the low-doped region to grow a SAG structure; and diffusing through the SAG structure to form a second high-doped region in the low-doped region.

An avalanche photodiode with a diffused junction and the method for its fabrication are disclosed. The method comprising forming, on a substrate, a first high-doped region and a low-doped region; performing selective area growth (SAG) with in-situ etchant on the low-doped region to grow a SAG structure; and diffusing through the SAG structure to form a second high-doped region in the low-doped region.

The present disclosure provides a light detecting device. The light detecting devices includes an insulating layer, a silicon layer, a light detecting layer, N first doped regions and M second doped regions. The silicon layer is disposed over the insulating layer. The light detecting layer is disposed over the silicon layer and extends within at least a portion of the silicon layer. The first doped regions have a first dopant type and are disposed within the light detecting layer. The second doped regions have a second dopant type and are disposed within the light detecting layer. The first doped regions and the second doped regions are alternatingly arranged. M and N are integers equal to or greater than 2.

A semiconductor laminate includes a substrate formed of a group III-V compound semiconductor and a quantum well structure disposed on the substrate. The quantum well structure includes a second element layer formed of a group III-V compound semiconductor and containing Sb and a first element layer formed of a group III-V compound semiconductor and disposed in contact with the second element layer. In the first element layer, the thickness of a region in which the content of Sb decreases in a direction away from the substrate from 80% of the maximum content of Sb in the second element layer to 6% of the maximum content is from 0.5 nm to 3.0 nm inclusive.

A photovoltaic cell can include a dopant in contact with a semiconductor layer.

A stacked III-V semiconductor photonic device having a second metallic terminal contact layer at least formed in regions, a highly doped first semiconductor contact region of a first conductivity type, a very low doped absorption region of the first or second conductivity type having a layer thickness of 20 μm-2000 μm, a first metallic terminal contact layer, wherein the first semiconductor contact region extends into the absorption region in a trough shape, the second metallic terminal contact layer is integrally bonded to the first semiconductor contact region and the first metallic terminal contact layer is arranged below the absorption region. In addition, the stacked III-V semiconductor photonic device has a doped III-V semiconductor passivation layer of the first or second conductivity type, wherein the III-V semiconductor passivation layer is arranged at a first distance of at least 10 μm to the first semiconductor contact region.

Provided is an infrared detector capable of achieving high sensitivity with little noise. An infrared detector includes: contact layers; a photoelectric conversion layer; a barrier layer; and an insertion layer. Each of the contact layers is doped with a dopant. The photoelectric conversion layer is placed between the contact layers, and includes a quantum layer (quantum dots) and an intermediate layer. The barrier layer is placed between the photoelectric conversion layer and one of the contact layers. The insertion layer is placed between, and in contact with, the photoelectric conversion layer and the one contact layer.