Silicon (c-Si) Wafers for Research & Development 

Crystalline silicon (c-Si) wafers and amorphous/c-Si stacks are widely used to fabricate low-temperature BEOL-compatible Schottky diodes, high-efficiency silicon solar cells, and metasurface holograms. UniversityWafer, Inc. supplies 4" and 6" silicon wafers, thermal oxide coated substrates, doped amorphous Si layers, and silicon-on-sapphire (SOS) wafers to support advanced device and photovoltaic research.

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Crystalline Silicon Wafers for Advanced Semiconductor Research

Crystalline silicon (c-Si) wafers provide a highly controlled substrate platform for semiconductor device fabrication, thin-film research, microelectronics, photonics, MEMS, and experimental device structures. Researchers can specify crystal orientation, conductivity type, dopant, resistivity, thickness, surface finish, and deposited films according to their fabrication requirements.

UniversityWafer supplies crystalline silicon substrates as well as wafers with thermal oxide, amorphous silicon, epitaxial silicon, and other deposited layers for specialized research.

Low-Temperature BEOL-Compatible Schottky Diode Research

One research application involves developing Schottky-contact diodes using low-temperature deposited silicon. A Ph.D. researcher requested a silicon substrate stack containing doped amorphous silicon for investigating device fabrication at temperatures below approximately 400°C.

“We need Si wafers with a layer of n-type doped amorphous silicon on top, with a target doping concentration in the range of approximately 1018–1019 cm-3.

We are planning to fabricate low-temperature BEOL-compatible Schottky-contact diodes using doped amorphous silicon. Previous work demonstrated the concept with phosphorus-doped crystalline silicon and polycrystalline silicon deposited at approximately 600°C. We now plan to investigate whether the device can be fabricated using amorphous silicon deposited below 400°C for improved BEOL compatibility.”

Requested substrate stack, from bottom to top:

  1. 100 mm (4-inch) silicon wafer
    P-type, (100) orientation, approximately 1–20 Ω·cm resistivity, single-side polished, test grade.
  2. Thermal silicon dioxide (SiO2)
    Approximately 1000 Å (100 nm) thermal oxide on both sides.
  3. N-type amorphous silicon (a-Si)
    Approximately 1000–2000 Å (100–200 nm) thick with target donor concentrations around 1018 and 1019 cm-3.

Reference #273070 for specifications and pricing.

Why Low-Temperature Processing Matters for BEOL

Back-end-of-line (BEOL) processing occurs after many of the temperature-sensitive device structures and interconnect layers have already been fabricated. As a result, additional processing steps may need to remain within a restricted thermal budget.

Depositing semiconductor films at lower temperatures can therefore be valuable when researchers want to integrate additional devices without exposing existing structures to the higher temperatures normally associated with some crystalline or polycrystalline silicon processes.

Amorphous silicon (a-Si) is particularly interesting for this type of research because it can be deposited as a thin film at substantially lower temperatures than conventional high-temperature crystalline-silicon processing.

Crystalline Silicon vs. Amorphous Silicon

Although both materials consist primarily of silicon, their atomic structures are fundamentally different.

Crystalline silicon (c-Si) has long-range atomic order and, under ambient conditions, adopts the diamond-cubic crystal structure. Its controlled crystallographic structure makes it the standard substrate material for many semiconductor and microfabrication processes.

Amorphous silicon (a-Si) lacks long-range crystalline order and is generally deposited as a thin film. Its electrical and optical properties depend strongly on deposition conditions, hydrogen content, defects, and doping.

Polycrystalline silicon (poly-Si) represents another form of silicon. It contains many crystalline grains separated by grain boundaries and is widely used in semiconductor structures, electrodes, gates, MEMS, and thin-film research.

Schottky Contacts on Silicon

A Schottky contact is formed at an appropriate metal-semiconductor interface. Unlike a conventional p-n junction, its electrical behavior depends strongly on the properties of the metal-semiconductor interface, including the semiconductor doping, interface states, processing history, and contact material.

Researchers can investigate Schottky structures using crystalline silicon, polycrystalline silicon, or deposited amorphous silicon depending on the device architecture and process-temperature requirements.

Controlled substrate resistivity and semiconductor doping are particularly important because they influence carrier transport, depletion behavior, contact resistance, and device characteristics.

Thermal Oxide as an Electrical Isolation Layer

The requested BEOL research stack includes approximately 100 nm of thermal silicon dioxide (SiO2). Thermal oxide is commonly used as a high-quality insulating and dielectric layer on crystalline silicon.

Depending on device design, SiO2 can provide electrical isolation, surface passivation, masking, or a defined interface for subsequent thin-film processing.

Explore thermal oxide coated silicon wafers for research requiring controlled SiO2 thicknesses on silicon substrates.

Crystalline Silicon on Sapphire (SOS)

Crystalline silicon can also be integrated with insulating substrates. Silicon-on-sapphire (SOS) consists of a crystalline silicon layer grown on a sapphire (Al2O3) substrate.

SOS combines the useful electronic and nanofabrication properties of crystalline silicon with the electrical insulation and optical properties of sapphire. Depending on layer thickness and device design, this platform can be useful for photonics, metasurfaces, RF devices, sensors, microelectronics, and optical research.

Learn more about silicon-on-sapphire wafers .

Silicon-on-Sapphire for Metasurface Holograms

Researchers have used thin crystalline silicon layers on sapphire to fabricate dielectric metasurfaces and holographic optical structures. Patterning the high-index silicon layer into subwavelength structures allows researchers to manipulate properties of transmitted or reflected light, depending on the metasurface design.

One example of an SOS substrate supplied for this type of research included:

  • Wafer diameter: 100 mm (4 inch)
  • Substrate: Double-side-polished sapphire
  • Sapphire thickness: 460 ± 20 µm
  • Silicon layer: Epitaxial crystalline silicon
  • Silicon orientation: <100>
  • Silicon thickness: approximately 230 nm ±10%
  • Resistivity: >100 Ω·cm

Other silicon-layer thicknesses may be available depending on research requirements. Contact UniversityWafer for current specifications and availability.

Crystalline silicon on sapphire substrate used for metasurface hologram fabrication

Example Application: Fabricated Metasurface Holograms

Applications of Crystalline Silicon Substrates

The combination of mature processing technology, controllable electrical properties, high-quality surfaces, and well-characterized crystal structure makes c-Si useful across a wide range of research applications, including:

  • CMOS and semiconductor device research
  • Schottky diodes and metal-semiconductor contacts
  • Low-temperature BEOL device integration
  • MEMS and microsensors
  • Microfabrication and nanofabrication
  • Metasurfaces and optical devices
  • Silicon photonics
  • Thin-film deposition research
  • Solar cells and photovoltaic research
  • Materials characterization

Selecting a Crystalline Silicon Wafer

The correct substrate depends on the fabrication process and final device. Important specifications may include wafer diameter, thickness, crystal orientation, conductivity type, dopant, resistivity, surface finish, TTV, bow, warp, and deposited film requirements.

UniversityWafer supplies crystalline silicon wafers and custom thin-film substrate configurations for semiconductor, microfabrication, photonics, MEMS, and materials-science research.

Get Your Crystalline Silicon Wafer Quote FAST! Or, Buy Wafers Online and Start Researching Today!





Crystalline Silicon (c-Si) for Solar Cells and Semiconductor Research

Crystalline silicon (c-Si) is one of the most important semiconductor materials used in modern electronics and photovoltaic technology. Its well-ordered crystal structure provides predictable electrical, optical, mechanical, and thermal properties that make it suitable for solar cells, integrated circuits, MEMS, sensors, and semiconductor research.

In photovoltaic applications, crystalline silicon serves as the semiconductor absorber in most conventional silicon solar cells. Researchers can control its electrical properties through doping, surface processing, passivation, and the formation of semiconductor junctions and contacts.

Crystalline silicon c-Si substrate applications including BEOL Schottky diodes, silicon heterojunction solar cells, silicon-on-sapphire photonics, MEMS and semiconductor devices

What Is Crystalline Silicon (c-Si)?

Crystalline silicon is solid silicon in which atoms are arranged in a long-range ordered crystal lattice. At ambient conditions, silicon adopts the diamond-cubic crystal structure, in which each silicon atom is covalently bonded to four neighboring silicon atoms.

This ordered structure distinguishes crystalline silicon from amorphous silicon (a-Si), which lacks long-range crystalline order. Crystalline silicon can be produced as a single crystal or as a polycrystalline material containing many individual crystal grains.

Learn more about monocrystalline silicon and its use as a semiconductor substrate.

Monocrystalline vs. Polycrystalline Silicon

Monocrystalline silicon consists of a continuous single-crystal lattice across the material. Semiconductor-grade single-crystal silicon is commonly grown using the Czochralski (CZ) or Float-Zone (FZ) process.

Polycrystalline or multicrystalline silicon, by contrast, contains multiple crystalline grains separated by grain boundaries. These boundaries can influence carrier transport and recombination, making the microstructure an important consideration in photovoltaic and electronic applications.

For research requiring carefully controlled crystal orientation, resistivity, doping, surface quality, and defect density, single-crystal silicon wafers provide a highly controlled substrate platform.

Crystalline Silicon vs. Amorphous Silicon

Crystalline and amorphous silicon are both used in photovoltaic technology, but their atomic structures and electronic properties are substantially different.

Crystalline silicon has long-range atomic order and an indirect band gap of approximately 1.12 eV at room temperature. It is widely used for conventional wafer-based photovoltaic cells.

Amorphous silicon lacks long-range crystalline order. Hydrogenated amorphous silicon (a-Si:H) is commonly deposited as a thin film and can be used in thin-film photovoltaics as well as in passivation and heterojunction structures.

These materials should not be confused with nanocrystalline or microcrystalline silicon. Nanocrystalline silicon contains very small crystalline silicon regions and therefore is not simply another name for amorphous silicon.

Why Is Crystalline Silicon Used in Solar Cells?

Crystalline silicon combines several properties that make it well suited to photovoltaic devices. Silicon is abundant, its semiconductor behavior is extensively understood, and mature wafer-processing technologies allow researchers and manufacturers to precisely control doping, junction formation, surface texture, passivation, and electrical contacts.

When photons with sufficient energy are absorbed in the semiconductor, they can generate electron-hole pairs. A properly designed photovoltaic junction separates these photogenerated carriers, allowing electrical power to be extracted through external contacts.

Solar-cell performance depends on much more than wafer size. Important factors include material quality, minority-carrier lifetime, surface recombination, optical losses, resistive losses, doping, passivation, contact design, and device architecture.

P-Type and N-Type c-Si Wafers

Crystalline silicon wafers can be produced as either p-type or n-type material by introducing controlled concentrations of electrically active dopants.

P-type silicon is commonly produced using acceptor dopants such as boron, while n-type silicon is commonly produced using donor dopants such as phosphorus.

The appropriate conductivity type and resistivity depend on the intended solar-cell architecture, fabrication process, and research objective.

Silicon Heterojunction Solar Cells

Silicon heterojunction (SHJ or HJT) solar cells combine a crystalline silicon wafer with thin layers of hydrogenated amorphous silicon. These thin films can provide excellent surface passivation while helping form carrier-selective junctions.

Transparent conductive oxide layers, such as indium tin oxide (ITO) , may also be incorporated to provide optical transparency and lateral electrical conduction.

This combination of c-Si, a-Si:H, and transparent conductive materials is widely studied for high-performance photovoltaic devices and advanced tandem solar-cell architectures.

Crystalline Silicon in Tandem Solar Cells

Crystalline silicon can also serve as the bottom-cell absorber in tandem photovoltaic devices. In these architectures, a higher-band-gap top cell absorbs higher-energy photons while the silicon bottom cell converts a portion of the longer-wavelength light transmitted through the top device.

Perovskite/silicon tandems are an important research example. By combining absorbers with complementary spectral response, tandem architectures can potentially achieve conversion efficiencies beyond those obtainable from a conventional single-junction silicon solar cell.

Silicon Wafer Orientation for Solar-Cell Research

Silicon wafers are available with crystallographic orientations such as (100), (110), and (111). Orientation affects surface atomic arrangement, oxidation, etching behavior, mechanical properties, and some fabrication processes.

Si(100) is widely used in semiconductor processing and silicon solar-cell research. Other orientations can be useful for specialized experiments, particularly where anisotropic etching, surface structure, cleavage, or crystallographic effects are being investigated.

Learn more about silicon wafer orientation when selecting substrates for a specific process.

Surface Texture and Light Management

Efficient solar cells are designed to minimize optical losses. Surface texturing can reduce reflection and increase the effective optical path of incoming light within the silicon absorber.

Crystallographic orientation is important because common anisotropic wet etchants remove different silicon crystal planes at different rates. On appropriately oriented wafers, this behavior can be used to create microscopic surface structures for optical and microfabrication research.

Anti-reflection and passivation layers may also be deposited on the silicon surface to reduce optical reflection and electronic recombination.

Six-Inch Silicon Wafers for Photovoltaic Research

150 mm (6-inch) silicon wafers provide a useful research platform for photovoltaic device fabrication, thin-film deposition, surface passivation, coating development, and semiconductor processing.

Researchers can specify parameters such as wafer diameter, thickness, crystal orientation, conductivity type, dopant, resistivity, surface finish, and other material requirements according to their experimental process.

Applications of Crystalline Silicon Wafers

Although photovoltaics are an important application, crystalline silicon substrates are used across a much broader range of research and manufacturing technologies, including:

  • Crystalline silicon solar cells
  • Silicon heterojunction (HJT/SHJ) solar cells
  • Perovskite-silicon tandem photovoltaics
  • Integrated circuits and CMOS research
  • MEMS sensors and actuators
  • Microfabrication and nanofabrication
  • Silicon photonics
  • Thin-film deposition experiments
  • Surface passivation research
  • Semiconductor materials characterization

Selecting c-Si Wafers for Research

Selecting a crystalline silicon substrate requires more than choosing wafer diameter. Depending on the application, researchers may need to specify crystal orientation, thickness, dopant, conductivity type, resistivity, surface finish, TTV, bow, warp, and crystal growth method.

UniversityWafer supplies crystalline silicon wafers for photovoltaic research, semiconductor fabrication, MEMS, microelectronics, photonics, and materials-science applications.

Related Crystalline Silicon Resources

Explore related silicon substrates, thin films, semiconductor materials, and fabrication technologies for electronics, photonics, MEMS, and photovoltaic research.

  • Silicon Wafers – Explore crystalline silicon substrates available with different orientations, dopants, resistivities, thicknesses, and surface finishes.
  • Monocrystalline Silicon Wafers – Learn about single-crystal silicon and its use in semiconductor, photovoltaic, MEMS, and materials research.
  • Amorphous Silicon (a-Si) – Compare amorphous silicon thin films with crystalline silicon for low-temperature processing and device research.
  • Polycrystalline Silicon (Poly-Si) – Explore poly-Si materials used in semiconductor devices, MEMS, electrodes, gates, and thin-film research.
  • P-Type Silicon Wafers – Learn about acceptor-doped crystalline silicon substrates and their semiconductor and photovoltaic applications.
  • Thermal Oxide Silicon Wafers – Explore SiO2-coated silicon substrates for dielectric isolation, device fabrication, and thin-film research.
  • Silicon-on-Sapphire (SOS) Wafers – Discover crystalline silicon layers on sapphire for photonics, metasurfaces, sensors, RF devices, and optical research.
  • Silicon Epitaxy – Learn about epitaxial crystalline silicon layers for advanced semiconductor structures and device development.
  • 6-Inch Silicon Wafers – Explore 150 mm silicon substrates for semiconductor processing, thin-film deposition, and photovoltaic research.
  • Silicon Wafers for Solar Cells – Learn about silicon substrates used in photovoltaic and advanced solar-cell research.
  • Semiconductor Band Gap – Learn how semiconductor band structure and band-gap energy influence electronic and optoelectronic devices.
  • Microfabrication – Explore wafer-based fabrication processes for semiconductor, MEMS, photonic, and microscale devices.