Xerox Corporation

Palo Alto Research Center Inc.

Palo Alto Research Corporation Incorporated

Christian G Van De Walle

Michael A Kneissl

David P Bour

Linda T Romano

Peter Kiesel

Noble Marshall Johnson

William S Wong

Thomas Hantschel

Raj B Apte

Thomas L Paoli

Jeng Ping Lu

Oliver Schmidt

David G Duff

John E Northrup

Stephen David White

Alberto Salleo

Ping Mei

Norbert H Nickel

Kiesel Peter

Systems and methods may provide electrical contacts to an array of substantially vertically aligned nanorods. The nanorod array may be fabricated on top of a conducting layer that serves as a bottom contact to the nanorods. A top metal contact may be applied to a plurality of nanorods of the nanorod array. The contacts may allow I/V (current/voltage) characteristics of the nanorods to be measured.

Systems and methods for electrical contacts to arrays of vertically aligned nanorods

An improved fuel cell is described. The invention addresses the problem of mechanical failure in thin electrolytes. One embodiment varies the thickness of the electrolyte and positions at least either the anode or cathode in the recessed region to provide a short travel distance for ions traveling from the anode to the cathode or from the cathode to the anode. A second embodiment uses a uniquely shaped manifold cover to allow close positioning of the anode to the cathode. Using the described structures results in a substantial improvement in fuel cell reliability and performance.

Micro-machined fuel cells

A semiconductor device has a heterostructure including a first layer of semiconductor oxide material. A second layer of semiconductor oxide material is formed on the first layer of semiconductor oxide material such that a two dimensional electron gas builds up at an interface between the first and second materials. A passivation layer on the outer surface stabilizes the structure. The device also has a source contact and a drain contact.

Method for surfaced-passivated zinc-oxide

Surface-passivated zinc-oxide based sensor

A nitride-based laser diode structure utilizing a single GaN:Mg waveguide/cladding layer, in place of separate GaN:Mg waveguide and AlGaN:Mg cladding layers used in conventional nitride-based laser diode structures. When formed using an optimal thickness, the GaN:Mg layer produces an optical confinement that is comparable to or better than conventional structures. A thin AlGaN tunnel barrier layer is provided between the multiple quantum well and a lower portion of the GaN:Mg waveguide layer, which suppresses electron leakage without any significant decrease in optical confinement. A split-metal electrode is formed on the GaN:Mg upper waveguide structure to avoid absorption losses in the upper electrode metal. A pair of AlGaN:Si current blocking layer sections are located below the split-metal electrode sections, and separated by a gap located over the active region of the multiple quantum well.

Nitride-based laser diode with GaN waveguide/cladding layer

A nitride-based laser diode structure utilizing a metal-oxide (e.g., Indium-Tin-Oxide (ITO) or Zinc-Oxide (ZnO)) in place of p-doped AlGaN to form the upper cladding layer. An InGaN laser diode structure utilizes ITO upper cladding structure, with an SiOisolation structure formed on opposite sides of the ITO upper cladding structure to provide a lateral index step that is large enough to enable lateral single-mode operation. The lateral index step is further increased by slightly etching the GaN:Mg waveguide layer below the SiOisolation structure. An optional p-type current barrier layer (e.g., AlGaN:Mg having a thickness of approximatelynm) is formed between the InGaN-MQW region and a p-GaN upper waveguide layer to impede electron leakage from the InGaN-MQW region.

Laser diode with metal-oxide upper cladding layer

A p-n tunnel junction between a p-type semiconductor layer and a n-type semiconductor layer provides current injection for an edge-emitting nitride based semiconductor laser structure. The amount of p-type material in the nitride based semiconductor laser structure can be minimized, with attendant advantages in electrical, thermal, and optical performance, and in fabrication.

Edge-emitting nitride-based laser diode with p-n tunnel junction current injection

The performance of nitride based diodes is currently limited by the resistivity of the ohmic contacts to the p-type GaN. The large value of the contact resistance contributes to a large voltage for device operation. This in turn causes device heating, making cw operation difficult and limiting the device lifetime. A layer of GaP or GaNP alloy between the GaN and the metal contact layer serves to bridge the energetic barrier between the GaN valence band and the metal Fermi level, thus enhancing the hole injection and reducing the contact resistance.

Semiconductor structures having reduced contact resistance

A semiconductor device includes group III-V layers formed over a substrate. At least one of the group III-V layers is doped with a dopant. The dopant includes a first dopant and one of a second dopant and an isovalent impurity. The first dopant has a covalent radius different in size than the covalent radii of each of the second dopant and the isovalent impurity.

Semiconductor device and method of forming a semiconductor device

An index-guided buried heterostructure AlGaInN laser diode provides improved mode stability and low threshold current when compared to conventional ridge waveguide structures. A short period superlattice is used to allow adequate cladding layer thickness for confinement without cracking. The intensity of the light lost due to leakage is reduced by about 2 orders of magnitude with an accompanying improvement in the far-field radiation pattern when compared to conventional structures.

Structure and method for index-guided buried heterostructure AlGalnN laser diodes

A self aligned, index-guided, buried heterostructure AlGalnN laser diode provides improved mode stability and low threshold current when compared to conventional ridge waveguide structures. A short period superlattice is used to allow adequate cladding layer thickness for confinement without cracking. The intensity of the light lost due to leakage is reduced by about 2 orders of magnitude with an accompanying improvement in the far-field radiation pattern when compared to conventional structures. The comparatively large p-contact area allowed by the self-aligned architecture contributes to a lower diode voltage and less heat during continuous wave operation of the laser diode.

Structure and method for self-aligned, index-guided, buried heterostructure AlGalnN laser diodes

A structure and method for an asymmetric waveguide nitride laser diode without need of a p-type waveguide is disclosed. The need for a high aluminum tunnel barrier layer in the laser is avoided.

Growing community of inventors

Sunnyvale, CA, United States of America

Christian G Van De Walle