Rosestreet Labs Energy, Inc.

University of California

Cree Gmbh

Cornell Research Foundation Inc.

Wladyslaw Walukiewicz

Kin Man Yu

Lothar Reichertz

Iulian Gherasoiu

Junqiao Wu

Joel W Ager, Iii

Umesh Kumar Mishra

Yifeng Wu

Stacia Keller

William J Schaff

Prashant Chavarkar

Ioulia P Smorchkova

A light emitting device includes a substrate, multiple n-type layers, and multiple p-type layers. The n-type layers and the p-type layers each include a group III nitride alloy. At least one of the n-type layers is a compositionally graded n-type group III nitride, and at least one of the p-type layers is a compositionally graded p-type group III nitride. A first ohmic contact for injecting current is formed on the substrate, and a second ohmic contact is formed on a surface of at least one of the p-type layers. Utilizing the disclosed structure and methods, a device capable of emitting light over a wide spectrum may be made without the use of phosphor materials.

Multi-color light emitting devices with compositionally graded cladding group III-nitride layers grown on substrates

A photovoltaic device having three dimensional (3D) charge separation and collection, where charge separation occurs in 3D depletion regions formed between a p-type doped group III-nitride material in the photovoltaic device and intrinsic structural imperfections extending through the material. The p-type group III-nitride alloy is compositionally graded to straddle the Fermi level pinning by the intrinsic structural imperfections in the material at different locations in the group III-nitride alloy. A field close to the surfaces of the intrinsic defects separates photoexcited electron-hole pairs and drives the separated electrons to accumulate at the surfaces of the intrinsic defects. The intrinsic defects function as n-type conductors and transport the accumulated electrons to the material surface for collection. The compositional grading also creates a potential that drives the accumulated separated electrons toward an n-type group III-nitride layer for collection. The p-type group III-nitride alloy may comprise an alloy of InGaN, InAlN or InGaAlN.

Photovoltaic device with three dimensional charge separation and collection

An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

Dilute group III-V nitride intermediate band solar cells with contact blocking layers

Dilute Group III-V nitride intermediate band solar cells with contact blocking layers

The highly mismatched alloy ZnMnOTe, 0&#x2266;y&#x3c;1 and 0&#x3c;x&#x3c;1 and other Group II-IV-Oxygen implanted alloys have been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of extended states located within the band gap of the ZnMnTe host. With multiple band gaps that fall within the solar energy spectrum, ZnMnOTeis a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

Multiband semiconductor compositions for photovoltaic devices

A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

Single P-N junction tandem photovoltaic device

An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is InGaN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.

Broad spectrum solar cell

A Group III nitride based high electron mobility transistors (HEMT) is disclosed that provides improved high frequency performance. One embodiment of the HEMT comprises a GaN buffer layer, with an AlGaN (y=1 or y 1) layer on the GaN buffer layer. An AlGaN (0&#x2266;x&#x2266;0.5) barrier layer on to the AlGaN layer, opposite the GaN buffer layer, AlGaN layer having a higher Al concentration than that of the AlGaN barrier layer. A preferred AlGaN layer has y=1 or y1 and a preferred AlGaN barrier layer has 0&#x2266;x&#x2266;0.5. A 2DEG forms at the interface between the GaN buffer layer and the AlGaN layer. Respective source, drain and gate contacts are formed on the AlGaN barrier layer. The HEMT can also comprising a substrate adjacent to the buffer layer, opposite the AlGaN layer and a nucleation layer between the AlGaN buffer layer and the substrate.

Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer

Non-alloyed, low resistivity contacts for semiconductors using Group III-V and Group II-VI compounds and methods of making are disclosed. Co-implantation techniques are disclosed.

Growing community of inventors

Kensington, CA, United States of America

Wladyslaw Walukiewicz