Semiconductors & Integrated Circuits

Semiconductors & Integrated Circuits Portfolios

Most Recent Inventions

Real-Time Monitoring of Sputtered Thin Films

UW–Madison researchers have developed methods that combine off-axis sputter deposition with in situ RHEED analysis. Using a new multi-gun approach, films are grown and monitored in a single vacuum chamber that houses components of both systems. In this setup the sputtering magnets are used to align the RHEED electron beam. The problem of beam deflection is addressed by applying antisymmetric magnet configurations to the assembly, resulting in a highly predictable bending of the beam.

Single-Crystal Halide Perovskite Nanowires with Superior Performance

Metal halide perovskite-based material is emerging as a “superstar” semiconductor material for cost-effective photovoltaic applications. UW–Madison researchers have developed a practical solution growth method for producing single-crystal perovskite nanowires with superior material quality and lasing performance.

Specifically the new method is based on a facile process of low-temperature dissolution of a metal precursor film in a cation precursor solution, followed by recrystallization to form single-crystal perovskite nanostructures such as nanowires, nanorods and nanoplates. Diverse families of metal halide perovskite materials with different cations, anions and dimensionality with different properties can be made to enable high-performance device applications.

Buffer Layer for Growing High Quality Semiconductors

A UW–Madison researcher has developed a method for forming a layer of mixed metal oxide epitaxial film (e.g., ScAlMgO4) on a sapphire semiconductor substrate. This layer provides a better lattice match than the uncoated sapphire substrate.

The mixed metal oxide layer is formed on the substrate via atomic layer deposition (ALD) and then annealed at a high temperature long enough to turn it into epitaxial film. The buffered substrate may then be used to grow a semiconductor.

Bottom-Up Patterning of Smooth Graphene Microstructures and Nanostructures

UW–Madison researchers have developed methods for growing patterned, single-crystalline graphene microstructures and nanostructures. Desired features and dimensions are shaped using a growth barrier ‘mask.’

First, a mask of suitable material (such as metal or metal oxide) is deposited in a desired pattern onto a substrate via any lithographic method. Graphene then is grown around the boundaries of the mask by chemical vapor deposition. The method can be used to produce a single layer or multilayer graphite.

Rapid, Controlled Growth of Doped Gallium Arsenide for Solar Cells

UW–Madison researchers have developed a new method for growing layers of carbon-doped GaAs using a haloalkane dopant and HVPE.

First, a substrate is exposed to a gas mixture composed of gallium, arsenic and a haloalkane dopant. Conditions in the reactor, including gas flow rate, growth temperature and timing, are controlled to grow layers of carbon-doped GaAs on the substrate via HVPE, and are adjustable to maximize dopant concentrations.

The process may be repeated to deposit additional layers. Also, a variety of haloalkanes based on bromine, chlorine and iodine can act as dopant. Using the new method, the concentration of carbon within the layer can be monitored and altered as needed.

Most Recent Patents

Zinc Oxide Thin Films Have Higher Electron Mobility

UW–Madison researchers have developed a room-temperature, solution-based surface treatment that improves the properties of zinc oxide film. The treatment uses molecules that bind to the film’s surface to increase electron mobility and conductivity.

In the process, a nanometer-thick film of polycrystalline zinc oxide or an alloy is disposed over a supporting substrate and a layer of organic carboxylic acid-containing molecules. The molecules can be derivatives of saturated fatty acids or photosensitizing dye. They bind to the surface of the film via their linkage groups.

The process is compatible with techniques for manufacturing large area electronics on flexible substrates.

Flexible Thin-Film Transistors for Mass Production

UW–Madison researchers have developed a new approach for fabricating high performance radiofrequency TFTs. Their method enables mass production and takes advantage of recent improvements in nanoimprinting lithography (NIL) technology.

The new TFTs include a trench cut into the semiconductor layer that separates the source and drain regions. The trench provides the TFTs with a unique current flow path that helps prevent several issues (e.g., short channel effect) that typically arise at this scale. The fabrication process is so fine that the length of the channel region is on the order of submicrons.

All-Glass Optical Microresonator for Single Molecule Spectroscopy and More

Building on their previous work, the researchers have developed all-glass microtoroidal resonators with improved sensitivity (i.e., superior Q/V ratio). Unlike their SiO2 on Si counterparts, the new resonators can be made chip scale – a significant advantage. Moreover, the use of glass in place of silicon makes the platform more desirable for applications including label-free sensing due to optical transparency in the visible region. Additionally, glass is a robust, chemically inert material and more biocompatible than silicon.

The new fabrication method follows the same general scheme as the previously developed oxide-on-silicon toroids, but the materials are inverted. This results in a silicon toroid atop an oxide pillar, followed by thermal oxidation to form an all-glass structure in the final step.