Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/26—Deposition of carbon only
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/48—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating by irradiation, e.g. photolysis, radiolysis, particle radiation
  • C23C16/483—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating by irradiation, e.g. photolysis, radiolysis, particle radiation using coherent light, UV to IR, e.g. lasers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/72—Protective coatings, e.g. anti-static or antifriction
  • G11B5/727—Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
  • G11B5/8408—Processes or apparatus specially adapted for manufacturing record carriers protecting the magnetic layer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/20—Particle morphology extending in two dimensions, e.g. plate-like

Definitions

• the present disclosure relates to generally to two-dimensional amorphous carbon (2D AC) coating techniques. More particularly, the present disclosure is directed to an overcoat for magnetic recording media which provides good anti-corrosion property and high thermal stability. Disclosed embodiments are aimed to increase the areal density of storage media by improving the performance of heat assisted magnetic recording media (HAMR).
• HAMR heat assisted magnetic recording media
• the present disclosure provides a recording device comprising an overcoat layer, wherein the overcoat layer comprises an amorphous carbon overcoat layer having a crystallinity (C) ⁇ 0.8.
• the present disclosure provides a magnetic recording media device comprising a substrate layer; an adhesion layer; a heat sink layer; a soft under layer; another under layer; a recording layer; a capping layer; an overcoat layer, and a lubricant layer, wherein the overcoat layer comprises an amorphous carbon overcoat layer having a crystallinity (C) ⁇ 0.8.
• the present disclosure provides a method of manufacturing a recording device comprising applying an overcoat layer to a substrate, wherein the overcoat layer comprises an amorphous carbon overcoat layer having a crystallinity (C) ⁇ 0.8.
• the present disclosure provides a method of manufacturing a magnetic recording media device comprising a substrate layer; an adhesion layer; a heat sink layer; a soft under layer; another under layer; a recording layer; a capping layer; an overcoat layer, and a lubricant layer, and applying the overcoat layer to the substrate, wherein the overcoat layer comprises an amorphous carbon overcoat layer having a crystallinity (C) ⁇ 0.8.
• FIG. 1 is a schematic illustration showing the disclosed composite material of the atomically thin film showing random hexagon rings showing continuity and order (not graphene), according to one embodiment of the present disclosure.
• FIG. 2 illustrates a TEM image of an amorphous film showing the hexagons and non-hexagons, according to one embodiment of the present disclosure.
• FIG. 3 illustrates a measured thickness of the disclosed carbon film on boron nitride by Atomic Force Microscopy (AFM), according to one embodiment of the present disclosure.
• AFM Atomic Force Microscopy
• FIG. 4 illustrates a Raman spectra of amorphous film and nano-crystalline graphene on Si0 2 , according to one embodiment of the present disclosure.
• FIG. 5 illustrates TEM diffraction of atomically thin amorphous carbon (left) and graphene (right), according to one embodiment of the present disclosure.
• FIG. 6 illustrates the transmittance of the disclosed carbon film, according to one embodiment of the present disclosure.
• FIG. 7 illustrates a mechanical property of a 2D amorphous film and a demonstration of suspended carbon film, according to one embodiment of the present disclosure.
• FIG. 8 illustrates electrical properties of a 2DAC, according to one embodiment of the present disclosure.
• FIG. 9 illustrates composite material grown on different substrates, according to one embodiment of the present disclosure.
• FIG. 10 illustrates X-ray photoelectron spectroscopy (XPS) of a 2DAC on Cu, according to one embodiment of the present disclosure.
• XPS X-ray photoelectron spectroscopy
• FIG. 11 illustrates an exemplary cross section of magnetic disk used in HAMR technology, according to one embodiment of the present disclosure.
• FIG. 12 illustrates an exemplary water contact angle of the disclosed overcoat layer, according to one embodiment of the present disclosure.
• FIG. 13 is a graphical illustration comparing the thermal stability of commercial carbon overcoat with the disclosed overcoat, according to one embodiment of the present disclosure.
• FIG. 14 is a schematic illustration depicting a design for magnetic head used in HAMR media, according to one embodiment of the present disclosure.
• FIG. 15 is a graphical illustration comparing the reflectance of a commercial carbon overcoat with the disclosed overcoat, according to one embodiment of the present disclosure.
• FIG. l6a is a graphical illustration of a monolayer of amorphous carbon (MAC) transferred onto a Si0 2 /Si wafer, according to one embodiment of the present disclosure.
• FIG. 16b is a graphical illustration of an SEM image of a MAC suspended on a TEM grid, according to one embodiment of the present disclosure.
• FIG. 16c is a graphical illustration of Raman spectra of the disclosed amorphous carbon grown on different substrates, according to one embodiment of the present disclosure.
• FIG. l6d is a graphical illustration of Raman spectra for Cu growth, according to one embodiment of the present disclosure.
• FIG. l6e is a graphical illustration of Cls XPS spectra measured directly on different substrates, according to one embodiment of the present disclosure.
• FIG. l6f is a graphical illustration of high resolution Cls XPS spectra on Cu, according to one embodiment of the present disclosure.
• FIG. l7a illustrates a monochromated HRTEM image of the disclosed amorphous carbon monolayer, according to one embodiment of the present disclosure.
• FIG. l7b illustrates a large scale atom-by-atom mapping of the selected region in FIG. l7a, according to one embodiment of the present disclosure.
• FIG. l7c illustrates a zoom-in region highlighted by the outlined red square in FIG. l7b, according to one embodiment of the present disclosure.
• FIG. l7d illustrates a pair correlation function calculated by the mapping coordinate of each carbon atom, according to one embodiment of the present disclosure.
• FIG. l7e illustrates the comparison of the bond length distribution for the first neighboring atoms between graphene and the disclosed amorphous carbon monolayer, according to one embodiment of the present disclosure.
• FIG. l7f illustrates a statistical histogram of bond angle distribution between MAC and graphene, according to one embodiment of the present disclosure.
• FIG. l8a illustrates a force vs. deflection curve, according to one embodiment of the present disclosure.
• FIG. l8b illustrates a histogram of the 2D elastic stiffness of exemplary membranes, according to one embodiment of the present disclosure.
• FIG. l8c shows graph illustrating a 2D elastic modulus vs. pre-tension with linear fit (red line) and theoretical range, according to one embodiment of the present disclosure.
• FIG. l8d illustrates a theoretical simulation and AFM images of layers of MAC on
• Si02/Si according to one embodiment of the present disclosure.
• FIG. l8e illustrates a theoretical model used for simulations, according to one embodiment of the present disclosure.
• FIG. 18f illustrates a density of states (DOS) simulation, according to one embodiment of the present disclosure.
• FIG. l9a illustrates a SEM image of the two-terminal device, according to one embodiment of the present disclosure.
• FIG. l9b illustrates optical transmittance of 2D amorphous carbon, according to one embodiment of the present disclosure.
• FIG. l9c illustrates nonlinear I-V curves measured at five different temperatures, according to one embodiment of the present disclosure.
• FIG. l9d illustrates resistivity as a function of gate voltage for different temperatures measured, according to one embodiment of the present disclosure.
• FIG. l9e illustrates resistivity for samples with different layer numbers as a function of temperature, according to one embodiment of the present disclosure.
• FIG. l9f illustrates a linear fit of resistivity of offset vs. the power, according to one embodiment of the present disclosure.
• the term“comprising”, the term“having”, the term“including,” and variations of these words are intended to be open-ended and mean that there may be additional elements other than the listed elements.
• directional terms such as“top,”“bottom,” “upper,”“lower,”“above,”“below,”“left,”“right,”“horizontal,”“vertical,”“up,”“down,” etc., are used merely for convenience in describing the various embodiments of the present disclosure.
• the embodiments of the present disclosure may be oriented in various ways.
• the diagrams, apparatuses, etc., shown in the drawing Figures may be flipped over, rotated by 90° in any direction, reversed, etc.
• a value or property is“based” on a particular value, property, the satisfaction of a condition, or other factor, if that value is derived by performing a mathematical calculation or logical decision using that value, property or other factor.
• adheresion strength refers to the strength of the bonding between the disclosed 2D AC film to its growth substrate. It is directly dependent on the adhesion energy between these two materials, which may be measured in J/m 2 .
• amorphous carbon refers to carbon that does not have any long range crystalline structure.
• amorphous refers to lacking definite form or having no specific shape or being formless.
• amorphous refers to a solid that lacks the long-range order that is characteristic of a crystal.
• the term“atomically thin amorphous carbon” refers to amorphous carbon that consist of approximately one to five layers of carbon atoms in a plane, with predominantly sp 2 bonding between the carbon atoms and thus forming a layer. It should be appreciated that layers may be stacked, and this stacking of layers is considered within the scope of the invention.
• carbon coating refers to a layer of carbon deposited on a substrate.
• carbon ring size refers to the size of a ring of carbon atoms.
• the number of atoms in one carbon ring may vary from 4 to 9 atoms.
• the term“contact angle measurement” refers to a technique to measure the hydrophobicity of a surface. In an exemplary disclosed embodiment of a water droplet, this angle may be measured from the surface to the water-air interface. A small angle means that the surface favorably attracts water and a large angle suggests that the surface repels water.
• the term“computer hardware” and the term “hardware” refer to the digital circuitry and physical devices of a computer system, as opposed to computer software, which is stored on a hardware device such as a hard disk.
• Most computer hardware is not seen by normal users, because it is embedded within a variety of every day systems, such as in automobiles, microwave ovens, electrocardiograph machines, compact disc players, and video games, among many others.
• a typical personal computer consists of a case or chassis in a tower shape (desktop) and the following parts: motherboard, CPU, RAM, firmware, internal buses (PIC, PCI-E, USB, HyperTransport, CSI, AGP, VLB), external bus controllers (parallel port, serial port, USB, Firewire, SCSI.
• PS/2 PS/2, ISA, EISA, MCA), power supply, case control with cooling fan, storage controllers (CD- ROM, DVD, DVD-ROM, DVD Writer, DVD RAM Drive, Blu-ray, BD-ROM, BD Writer, floppy disk, USB Flash, tape drives, SATA, SAS), video controller, sound card, network controllers (modem, NIC), and peripherals, including mice, keyboards, pointing devices, gaming devices, scanner, webcam, audio devices, printers, monitors, etc.
• storage controllers CD- ROM, DVD, DVD-ROM, DVD Writer, DVD RAM Drive, Blu-ray, BD-ROM, BD Writer, floppy disk, USB Flash, tape drives, SATA, SAS
• video controller sound card
• network controllers modem, NIC
• peripherals including mice, keyboards, pointing devices, gaming devices, scanner, webcam, audio devices, printers, monitors, etc.
• the term“computer network” refers to a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. The most common types of computer networks in order of scale include: Personal Area Network (PAN), Local Area Network (LAN), Campus Area Network (CAN), Metropolitan Area Network (MAN), Wide Area Network (WAN), Global Area Network (GAN), Internetwork (intranet, extranet, Internet), and various types of wireless networks. All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly category 5 cable). Less common are microwave links (as in IEEE 802.11) or optical cable (“optical fiber”).
• the term“computer software” and the term “software” refers to one or more computer programs, procedures and documentation that perform some tasks on a computer system.
• the term includes application software such as word processors which perform productive tasks for users, system software such as operating systems, which interface with hardware to provide the necessary services for application software, and middleware which controls and co-ordinates distributed systems.
• Software may include websites, programs, video games, etc. that are coded by programming languages like C, C++, Java, etc.
• Computer software is usually regarded as anything but hardware, meaning the“hard” are the parts that are tangible (able to hold) while the“soft” part is the intangible objects inside the computer.
• Computer software is so called to distinguish it from computer hardware, which encompasses the physical interconnections and devices required to store and execute (or run) the software.
• software consists of a machine language specific to an individual processor.
• a machine language consists of groups of binary values signifying processor instructions which change the state of the computer from its preceding state.
• computer system refers to any type of computer system that implements software including an individual computer such as a personal computer, mainframe computer, mini-computer, etc.
• computer system refers to any type of network of computers, such as a network of computers in a business, the Internet, personal data assistant (PDA), devices such as a cell phone, a television, a videogame console, a compressed audio or video player such as an MP3 player, a DVD player, a microwave oven, etc.
• PDA personal data assistant
• a personal computer is one type of computer system that typically includes the following components: a case or chassis in a tower shape (desktop) and the following parts: motherboard, CPU, RAM, firmware, internal buses (PIC, PCI-E, USB, HyperTransport, CSI, AGP, VLB), external bus controllers (parallel port, serial port, USB, Firewire, SCSI.
• PS/2 PS/2, ISA, EISA, MCA), power supply, case control with cooling fan, storage controllers (CD-ROM, DVD, DVD-ROM, DVD Writer, DVD RAM Drive, Blu-ray, BD-ROM, BD Writer, floppy disk, USB Flash, tape drives, SATA, SAS), video controller, sound card, network controllers (modem, NIC), and peripherals, including mice, keyboards, pointing devices, gaming devices, scanner, webcam, audio devices, printers, monitors, etc.
• storage controllers CD-ROM, DVD, DVD-ROM, DVD Writer, DVD RAM Drive, Blu-ray, BD-ROM, BD Writer, floppy disk, USB Flash, tape drives, SATA, SAS
• video controller sound card
• network controllers modem, NIC
• peripherals including mice, keyboards, pointing devices, gaming devices, scanner, webcam, audio devices, printers, monitors, etc.
• the term“computer” refers to any type of computer or other device that implements software including an individual computer such as a personal computer, laptop computer, tablet computer, mainframe computer, mini-computer, etc.
• a computer also refers to electronic devices such as an electronic scientific instrument such as a spectrometer, a smartphone, an eBook reader, a cell phone, a television, a handheld electronic game console, a videogame console, a compressed audio or video player such as an MP3 player, a Blu-ray player, a DVD player, etc.
• the term“computer” refers to any type of network of computers, such as a network of computers in a business, a computer bank, the Cloud, the Internet, etc.
• Various processes of the present disclosure may be carried out using a computer.
• Various functions of the present disclosure may be performed by one or more computers.
• D/G ratio refers to the ratio of the intensities of the D and G peak in the Raman spectrum.
• the term“data storage medium” or“data storage device” refers to any medium or media on which a data may be stored for use by a computer system.
• Examples of data storage media include floppy disks, ZipTM disks, CD- ROM, CD-R, CD-RW, DVD, DVD-R, memory sticks, flash memory, hard disks, solid state disks, optical disks, etc.
• Two or more data storage media acting similarly to a single data storage medium may be referred to as a“data storage medium” for the purposes of the present disclosure.
• a data storage medium may be part of a computer.
• the term“data” means the reinterpretable representation of information in a formalized manner suitable for communication, interpretation, or processing.
• data may also be streaming data, a web service, etc.
• the term“data” is used to refer to one or more pieces of data.
• the term“database” or“data record” refers to a structured collection of records or data that is stored in a computer system.
• the structure is achieved by organizing the data according to a database model.
• the model in most common use today is the relational model.
• Other models such as the hierarchical model and the network model use a more explicit representation of relationships (see below for explanation of the various database models).
• a computer database relies upon software to organize the storage of data. This software is known as a database management system (DBMS).
• DBMS database management system
• Database management systems are categorized according to the database model that they support. The model tends to determine the query languages that are available to access the database.
• the term“diamond-like carbon” refers to amorphous carbon that consist of predominantly sp 3 bonding between carbon atoms.
• the term“differentiating stem cells” refers to the process of directing an unspecialized stem cell towards a specific type of cell with functional traits. In disclosed embodiments, the differentiation occurs due to a combination of chemical and substrate induced factors.
• electrochemical cell refers to a device capable of either generating electrical energy from chemical reactions or facilitating it otherwise.
• the electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and the other ones are called electrolytic cells which are used to drive chemical reactions like electrolysis.
• a common example of galvanic cells is a standard 1.5 - volt cell meant for consumer use.
• a battery may consist of one or more cells, connected in either parallel or series pattern.
• fuel cell refers to an electrochemical cell that converts the chemical energy from a fuel into electricity through an electrochemical reaction of hydrogen fuel with oxygen or another oxidizing agent.
• Fuel cells may differ from batteries in requiring a continuous source of fuel and oxygen (usually from air) to sustain the chemical reaction, whereas in a battery the chemical energy comes from chemicals already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.
• graphene refers to an allotrope (form) of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice. It is the basic structural element of many other allotropes of carbon, such as graphite, charcoal, carbon nanotubes and fullerenes. It can be considered as an indefinitely large aromatic molecule, the ultimate case of the family of flat polycyclic aromatic hydrocarbons. Graphene has many unusual properties including its strong materials properties, ability to efficiently conduct heat and electricity and is also nearly transparent.
• the term“hardware and/or software” refers to functions that may be performed by digital software, digital hardware, or a combination of both digital hardware and digital software. Various features of the present disclosure may be performed by hardware and/or software.
• the term“hydrophobic” refers to tending to repel or fail to mix with water.
• hydrophilcity refers to the property of repelling water rather than absorbing it or dissolving in it.
• the term“individual” refers to an individual mammal, such as a human being.
• the term“Internet” is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP). It is a“network of networks” that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.
• the Internet carries various information resources and services, such as electronic mail, online chat, file transfer and file sharing, online gaming, and the inter-linked hypertext documents and other resources of the World Wide Web (WWW).
• intranet refers to a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications that are under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users.
• an intranet is the internal network of an organization.
• a large intranet will typically have at least one web server to provide users with organizational information.
• Intranets may or may not have connections to the Internet. If connected to the Internet, the intranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet.
• the term“laser-assisted chemical vapor deposition (CVD)” refers to a synthesis method where a laser-heated substrate is exposed to one or more volatile precursors, which react or decompose on the surface to produce a deposit.
• the term“local area network (LAN)” refers to a network covering a small geographic area, like a home, office, or building.
• Current LANs are most likely to be based on Ethernet technology.
• the cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s.
• a wireless LAN may exist using a different IEEE protocol, 802.1 lb, 802. l lg or possibly 802.11h.
• the defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.
• Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s.
• machine-readable medium refers to any tangible or non-transitory medium that is capable of storing, encoding or carrying instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure, or that is capable of storing, encoding or carrying data structures utilized by or associated with such instructions.
• machine- readable medium includes, but is limited to, solid-state memories, and optical and magnetic media.
• machine -readable media include non-volatile memory, including by way of example, semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto optical disks; and CD-ROM and DVD-ROM disks.
• semiconductor memory devices e.g., EPROM, EEPROM, and flash memory devices
• magnetic disks such as internal hard disks and removable disks
• magneto optical disks and CD-ROM and DVD-ROM disks.
• the term“machine-readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more instructions or data structures.
• membrane refers to layer acting as a selective barrier that may allow some elements to pass through but stopping others such as molecules, ions, or other small particles.
• non-transient storage medium refers to a storage medium that is non-transitory, tangible and computer readable.
• Non transient storage medium may refer generally to any durable medium known in the art upon which data can be stored and later retrieved by data processing circuitry operably coupled with the medium.
• a non-limiting non-exclusive list of exemplary non-transitory data storage media may include magnetic data storage media (e.g., hard disc, data tape, etc.), solid state semiconductor data storage media (e.g., SDRAM, flash memory, ROM, etc.), and optical data storage media (e.g., compact optical disc, DVD, etc.).
• the term“processor” refers to a device that performs the basic operations in a computer.
• a microprocessor is one example of a processor
• the term“Raman spectroscopy” refers to a spectroscopic technique used to observe vibrational, rotational, and other low-frequency modes in a system. Raman spectroscopy is commonly used in chemistry to provide a structural fingerprint by which molecules can be identified. It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the vibrational modes in the system.
• the term“Raman spectrum” refers to a phenomenon of scattering intensity as a function of frequency shifts depending on rovibronic states of a molecule.
• Raman spectrum For a molecule to exhibit a Raman effect, there must be a change in its electric dipole-electric dipole polarizability with respect to the vibrational coordinate corresponding to the rovibronic state.
• the intensity of the Raman scattering is proportional to this polarizability change.
• RAM random-access memory
• the word random thus refers to the fact that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.
• the word RAM is mostly associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off.
• many other types of memory are RAM as well, including most types of ROM and a kind of flash memory called NOR-Flash.
• ratio of sp 3 /sp 2 refers to the type of carbon bonds found in the 2D AC. The sp 2 bonds allow for higher growth factor bonding.
• ROM read-only memory
• firmware software that is very closely tied to specific hardware, and unlikely to require frequent updates.
• ROM refers only to mask ROM (the oldest type of solid state ROM), which is fabricated with the desired data permanently stored in it, and thus can never be modified.
• modem types such as EPROM and flash EEPROM can be erased and re-programmed multiple times; they are still described as“read only memory” because the reprogramming process is generally infrequent, comparatively slow, and often does not permit random access writes to individual memory locations.
• the term“server” refers to a system (software and suitable computer hardware) that responds to requests across a computer network to provide, or help to provide, a network service.
• Servers can be run on a dedicated computer, which is also often referred to as“the server,” but many networked computers are capable of hosting servers.
• a computer can provide several services and have several servers running.
• Servers may operate within a client-server architecture and may comprise computer programs running to serve the requests of other programs - the clients. Thus, the server may perform some task on behalf of clients.
• the clients typically connect to the server through the network but may run on the same computer.
• IP Internet Protocol
• a server is a program that operates as a socket listener.
• Servers often provide essential services across a network, either to private users inside a large organization or to public users via the Internet.
• Typical computing servers are database server, file server, mail server, print server, web server, gaming server, application server, or some other kind of server.
• Numerous systems use this client/server networking model including Web sites and email services.
• An alternative model, peer-to-peer networking may enable all computers to act as either a server or client as needed.
• solid-state electronics refers to those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material.
• the term is often used to contrast with the earlier technologies of vacuum and gas-discharge tube devices and it is also conventional to exclude electro -mechanical devices (relays, switches, hard drives and other devices with moving parts) from the term solid state.
• solid-state can include crystalline, polycrystalline and amorphous solids and refer to electrical conductors, insulators and semiconductors, the building material is most often a crystalline semiconductor.
• Common solid-state devices include transistors, microprocessor chips, and RAM.
• flash RAM A specialized type of RAM called flash RAM is used in flash drives and more recently, solid state drives to replace mechanically rotating magnetic disc hard drives. More recently, the integrated circuit (IC), the light-emitting diode (LED), and the liquid-crystal display (LCD) have evolved as further examples of solid-state devices. In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it.
• the term“storage medium” refers to any form of storage that may be used to store bits of information.
• Examples of storage media include both volatile and non-volatile memories such as MRRAM, MRRAM, ERAM, flash memory, RFID tags, floppy disks, ZipTM disks, CD-ROM, CD-R, CD-RW, DVD, DVD-R, flash memory, hard disks, optical disks, etc.
• a“storage medium” Two or more storage media acting similarly to a single data storage medium may be referred to as a“storage medium” for the purposes of the present disclosure.
• a storage medium may be part of a computer.
• the term“substrate” refers to the structural support for the disclosed two-dimensional (2D) amorphous carbon film.
• disclosed embodiments provide a substrate to mechanically support, for example, the 2D AC film as, otherwise, the 2D AC film may be too thin to perform its function without getting damaged.
• the substrate may be regarded as the material used for growth of the disclosed 2D AC or 2D AC film on the surface of the substrate.
• the term“two-dimensional (2D) amorphous carbon film” refers to atomically thin amorphous carbon to the thinnest amorphous carbon possible (e.g., single atom thick) that can be grown directly, for example, on substrates including those having low melting temperature, are non-catalytic, and those substrates also including metal, glass and oxides surfaces. The growth on other substrates is made possible due to the low temperature at which the disclosed 2DAC film is grown.
• Disclosed embodiments of 2D AC film may be presented as a free-standing film or as a coating on a substrate as disclosed herein.
• the disclosed 2DAC film is amorphous, the carbon atoms bond to multiple adjacent carbon atoms in plane to form a strong network, which is very stable even when it is released from its growth substrate (free-standing).
• the carbon material also possesses properties for adhering to metal surfaces well, thereby ensuring full coverage across the substrate.
• the intrinsic thinness and the high strength of the disclosed 2D AC thin film also allow it to withstand bending of the metal substrate without breaking.
• the term“two-dimensional (2D) amorphous carbon coating” refers to a 2DAC film directly grown and/or deposited on a substrate. Disclosed embodiments may also include the case where the 2DAC coating is transferred onto or off the substrate.
• water contact angle refers.
• WAN wide area network
• WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
• WWW World Wide Web Consortium
• W3C World Wide Web Consortium
• W3C World Wide Web Consortium
• W3C World Wide Web Consortium
• W3C also engages in education and outreach, develops software and serves as an open forum for discussion about the Web.
• W3C standards include: CSS, CGI, DOM, GRDDL, HTML, OWL, RDF, SVG, SISR, SOAP, SMIL, SRGS, SSML, VoiceXML, XHTML+ Voice, WSDL, XACML.
• Magnetic media is widely used, for example, within data storage technology.
• Data storage technology may be utilized in a wide variety of applications including, for example, personal computers, cloud drive systems, internet implementations, etc.
• Areal density is a key factor for hard disk capacity and refers to the amount of data that can be stored on a unit area of storage medium.
• the data may be stored into the storage medium by switching the direction of magnetic bits in the storage medium.
• the size of individual magnetic bits may be reduced, which has a negative consequence of creating a weaker magnetic signal and lower signal-to-noise ratio.
• the read head is required to be brought closer to the magnetic surface to improve the signal-to-noise ratio.
• the head to surface distance greatly depends on the thickness of the carbon overcoat.
• the overcoat used in the current art includes a thickness of about 2.7nm. 1
• a carbon overcoat with a thickness of less than lnm is desired.
• the magnetic bits of the storage media become smaller, the magnetic bits need to possess a higher magnetization.
• the magnetic material should maintain a high coercivity in order to sustain a stable storage capacity.
• One example of employed materials includes a high magnetocrystalline anisotropy (Ku) Llo ordered FePt media. 2
• Ku magnetocrystalline anisotropy
• the high coercivity of the aforementioned material allows it to maintain stable storage using very small magnetic bits.
• the operation of the storage media is impacted as it is, therefore, more difficult for the write head to flip the magnetic direction of the bit.
• HAMR technology generally incudes an integrated laser in the read/write head to help heat up the magnetic bit up to its Curie temperature where the magnetic bits may be easily flipped. This facilitates easy writing of data.
• the magnetic device With a working environment under elevated temperature, it is a challenge for the magnetic device to have a thermally stable layer to provide good anti-corrosion protection.
• the carbon overcoat within the current prior art suffers from structural change and possible damage under the heating conditions of conventional HAMR technologies and processes.
• Embodiments of the present disclosure provide a new layer of overcoat to address the shortcomings of the prior art
• an amorphous carbon overcoat layer that can protect the underlying magnetic recording layer for heat assisted magnetic recording media (HAMR) is provided by disclosed embodiments, as described herein.
• the disclosed amorphous carbon overcoat layer can prevent corrosion of the media layer and reduce the friction between media and write head.
• the disclosed amorphous carbon overcoat is stable under such thermal conditions and is able to improve the overall performance of the HAMR media.
• Disclosed embodiments relate to a new composite material composed of an atomically thin (single layer) amorphous carbon on top of a substrate (metal, glass, oxides).
• a substrate metal, glass, oxides
• the amorphous carbon adheres very well to the substrate upon which it is grown.
• the amorphous carbon material provides unique characteristics.
• the disclosed amorphous carbon material is suitable for applications that utilize a substrate requiring a coating for a specific purpose(s). Exemplary applications may include, but not limited to, biomedical applications.
• the present disclosure provides a new form of carbon referred to as two- dimensional (2D) amorphous carbon (2DAC).
• Disclosed embodiments provide the thinnest amorphous carbon possible (e.g., approximately single atom thick) within the 2DAC that can be grown, for instance, directly on metallic substrates including those having low melting temperature, are non-catalytic, and also including glass and oxides surfaces.
• having a single atom thickness is a preferred material and may establish a lower thickness limit for the 2DAC.
• Disclosed embodiments may include a thickness that may range up to a few atom thickness (e.g., 10 atomic thickness or about 3+nm).
• the disclosed 2DAC may be provided as a two-dimensional (2D) amorphous carbon film. It remains important to note, however, that as the thickness of the disclosed 2D AC increases, it remains structurally different (e.g., sp 3 to sp 2 ratio) from any other possibly existing amorphous carbon material thickness, as disclosed herein.
• the growth on other substrates is made possible due to the low temperature at which the disclosed 2D AC film is grown.
• the disclosed 2D AC film is amorphous, the carbon atoms bond to multiple adjacent carbon atoms in plane to form a strong network, which is very stable even when it is released from its growth substrate (free-standing).
• each carbon atom is bonded to multiple carbon atoms such that there is a high density of bonds (connections).
• the disclosed 2DAC also possesses properties for adhering to metal surfaces well, thereby ensuring full coverage. Material properties (e.g., disclosed below), such as the intrinsic thinness and the high strength of the disclosed 2DAC thin film, also allow it to withstand bending of the metal substrate without breaking.
• amorphous carbon may be defined as a form of carbon with no long-range structural order. It exists in several forms and, depending on its form, is often called in different names like diamond-like carbon, glassy carbon, soot, etc.
• Amorphous carbon may be produced by several techniques including, for example, chemical vapor deposition, sputter deposition, and cathodic arc deposition among others. In convention applications, amorphous carbon has always existed in three-dimensional form (or in bulk). The two-dimensional equivalent form of carbon is graphene; however, graphene only exists as a crystalline material (either single crystal or polycrystalline). For graphene to be synthesized, it requires high temperatures and is mostly grown on copper.
• disclosed embodiments have managed to create a continuous two-dimensional form of amorphous carbon that is grown at a much lower temperature and on arbitrary substrates.
• the composite material of the disclosed 2D AC film and substrate has characteristics that are vastly different from the bulk amorphous carbon, and even to single layer graphene.
• Embodiments of the disclosed 2DAC may exist as a film, for example, coating a substrate, a film coating an internal surface of a porous structure, a suspended film, a rolled film, a tube, a fiber, or a hollow ball.
• the mechanical, electrical, optical, thermal and other properties of the disclosed 2D AC are expected to be varying, for example, depending on the shape of the 2D AC.
• a tube comprising the disclosed 2D AC will have high mechanical strength in the axial direction and softer response in the radial direction.
• FIG. 1 illustrates a schematic 100 of the disclosed composite materials with a TEM image of the carbon material on a top surface of a substrate.
• the composition of the disclosed matter is a new composite material of an atomically thin amorphous carbon 102 on top of a substrate 104 (e.g., metal or glass, oxides).
• the disclosed composite material may refer to an atomically thin 2D amorphous carbon (2DAC) on top of an arbitrary substrate.
• the disclosed 2DAC film on top of the disclosed substrate may be defined in terms of its atomic structure and its properties.
• FIG. 2 illustrates a TEM image of an amorphous film showing the hexagons and non-hexagons, according to one embodiment of the present disclosure.
• the upper left image of FIG. 2 illustrates a high resolution TEM image of the disclosed 2DAC film comprising hexagons and non-hexagons.
• a lower left schematic of the TEM image of the upper left image is provided to aid in viewing. Hexagons are colored in green, while non-hexagons are colored in either red or blue.
• the upper right display is an FFT illustrating which shows a ring structure with no clear diffraction patterns.
• a 2D AC film is a single-atom thick carbon film having a mixture of hexagon and non-hexagon rings in its structure.
• the rings are fully connected to each other, forming a network of polygons in large area film whose scale is at least in microns.
• the ratio of hexagons to non-hexagons is a measure of crystallinity (or amorphousity), C.
• Non-hexagons are in a form of 4-, 5-, 7-, 8-, 9-membered rings.
• a 2D amorphous film has C ⁇ 0.8, taken on a minimum imaged area of approximately 8.0 nm. 3
• the C value in FIG. 2 is approximately 0.65.
• the non-hexagons can be randomly distributed within the hexagonal matrix, or form along the boundaries of the hexagonal domains. The domains must not be greater than 5 nm.
• the fast Fourier transform (FFT) of the image must not show diffraction spots (FIG. 2, upper right).
• the 2D AC can be released from a substrate to be free-standing or can be transferred to other substrates.
• the disclosed 2DAC may be separating from the surface of the substrate to obtain a free-standing 2D AC film.
• FIG. 3 illustrates a measured thickness (i.e., the height) of the isolated disclosed 2DAC film on boron nitride (BN) by AFM. Based on the disclosed invention, the following properties apply: FIG. 3 shows the AFM of the disclosed transferred 2DAC film to boron nitride (BN). The disclosed thickness of the 2DAC is approximately 6 A, comparable to graphene which is only one atomic thick (thickness ranges from and including 3.3 A to 10 A when measured on BN). The thickness is also corroborated by the TEM image in FIG. 1. Further, the film is found to be homogenous.
• FIG. 4 illustrates Raman spectra 400 of amorphous film and non-crystalline graphene on Si0 2 .
• Raman spectroscopy of the isolated film showed no 2D peak (-2700 cm- 1), but instead showed broad G (at -1600 cm-l) and D peaks (at -1350 cm-l). The broadening of D and G peaks usually indicates a transition from nanocrystalline graphene to amorphous film as was previously reported. 4 From the intensity ratio of the D and G peaks, the domain size is estimated to be in the order of 1-5 nm. 4 Raman spectroscopy serves as a characterization tool to represent the TEM image in FIG. 2 in large area.
• FIG. 5 provides a comparison 500 of TEM diffraction of atomically thin amorphous carbon (left) and graphene (right), according to one embodiment of the present disclosure. Further evidence on the amorphous nature of the disclosed isolated film is corroborated by the TEM diffraction, where no clear diffraction spots are detected which is in contrast to graphene wherein diffraction spots are clearly seen indicating crystallinity.
• the diffraction rings in FIG. 7 (top) indicates a domain size of ⁇ 5 nm.
• the diffraction data of the amorphous film is consistent with the FFT image in FIG. 2. In this case, the 2DAC film is free-standing.
• a graph 600 illustrates the transparency of the disclosed carbon film, according to one embodiment of the present disclosure.
• the optical transparency is at ⁇ 98 % at 550 nm light wavelength, increasing in transparency with increasing wavelength.
• select embodiments provide an optical transparency equal to or greater than 98% at a wavelength of 550nm or higher.
• the disclosed carbon film differs from graphene as the transparency of graphene at a single layer is at a maximum of 97.7% throughout the visible wavelength (400nm-700nm, inclusive), and decreases as the number of layer increases.
• the transparency of the 2D AC film does not decrease rapidly at short wavelengths ( ⁇ 400nm) as seen in graphene.
• FIG. 7 illustrates non-indentation on suspended carbon film and suspended carbon film after exertion of ultimate stress by an Atomic Force Microscope (AFM) (e.g., Bruker model no: MPP-11120) tip.
• AFM Atomic Force Microscope
• the amorphous property of the disclosed 2DAC film prevents collapse of the suspended film in FIG. 7 (bottom). Instead, the film displays a ductile response to ultimate stress levels.
• FIG. 8 is a schematic illustration 800 of electrical properties of a 2D amorphous carbon, showing an I-V curve 802 of the 2D amorphous film and a histogram 804 of the measured resistivity values for a particular C value.
• a measurement technique/method is used towards generating a resistivity value.
• a ratio is used within the calculation from the data of I-V curve 802 to obtain each resistivity data point in histogram 804. Accordingly, length: width ratio for the 2D amorphous carbon in FIG. 8, left is 1:100.
• graphene has resistivity value of -10 6 W-cm while bulk glassy carbon (also 100% C-C sp 2 ) has values ranging from 0.01 to 0.001 W-cm.
• the monolayer film, containing n-membered rings > 6, is naturally a membrane that can selectively pass gases, ions, liquids or other species whose sizes are small enough to pass through the 7-,8-,9-membered rings.
• the disclosed 2D AC film can pass through proton lOx more efficient than crystalline monolayer boron nitride at room temperature. 6
• the resistivity to proton flow across the membrane is from 1 -10 W-cm 2 at room temperature.
• FIG. 9 illustrates composite material grown on different substrates, according to one embodiment of the present disclosure.
• Pictures of titanium, glass and copper coated with atomically thin amorphous carbon are illustrated on the left.
• the Raman spectra from the coated regions showing similar response irrespectively of the substrate.
• the Raman map of G/D peak ratio of the 2D AC film on top of the titanium shown its full coverage.
• the disclosed composite material i.e., the disclosed 2D AC and the substrate
• the 2DAC may be grown directly on any of the disclosed desired substrate materials.
• the disclosed composite material comprises an atomically thin ( ⁇ l nm) and continuous layer of two-dimensional amorphous carbon that is strongly bonded to a host substrate.
• the disclosed 2DAC film is formed as a continuous film over, preferably, substantially the entire substrate surface or at least the applied surface.
• the disclosed atomically thin 2D AC film disposed, for example, on Cu adheres very well to the substrate with an adhesion energy >200 J/m2.
• any attempts for transferring any 2D material to a material by convention materials and processes have previously led to defects and cracks, for example, in the transferred material(s) and also a reduction of coverage on the substrate. This is, at least in part, due to the fact that the transfer process generally employs many mechanical steps and may use chemicals that induce cracks and defects in conventional film applications.
• the disclosed 2D AC film does not need to be transferred, for example, from a growth substrate to a target substrate.
• enhanced characteristics of the disclosed 2DAC film provide and ensure consistent and full coverage directly across/over the substrate. Consistent and full coverage is thereby obtained, at least, because, there is no need to transfer the disclosed 2D AC film, since it is fully capable of consistently and successfully being grown directly on its host substrate.
• the disclosed 2D AC film is very suitable and dependable for applications that require additional physical characteristics/requirements of the 2DAC film and composite.
• Such physical characteristics may include the ability of the disclosed 2D AC film and/or composite to bend and/or stretch.
• the adhesion properties and ability of the disclosed 2D AC to the substrate ensures this is the case. If there is non-uniform adhesion to the substrate, like for transferred films, cracks in the film will form at regions of poor adhesion and are causes prone to failure.
• embodiments of the disclosed invention provide the top amorphous carbon film 102 covering the whole substrate 104 upon which it is grown (Raman map of FIG. 9) making it very useful for applications that require, for example, carbon coating.
• the top amorphous carbon film 102 also serves as a diffusion barrier without defects thereby preventing the underlying substrate from oxidation and corrosion. Due to electrically insulating properties, the disclosed amorphous carbon film 102 prevents any galvanic corrosion of substrate 104.
• the low electrical conductivity of the disclosed 2DAC is beneficial to cell attachment and proliferation as observed in recent reports. 8 Cells on conductive substrates adhere to the surface through electrostatic interactions without creating focal adhesions.
• Focal adhesions are crucial to cell proliferation and growth and a low electrical conductivity is preferred for focal adhesion development and cell proliferation.
• the low electrical conductivity is a consequence of the amorphous nature of the disclosed 2D AC as observed through the Raman spectroscopy D/G peak intensity and the sp 3 /sp 2 ratio.
• amorphous carbon film 102 material is a composite with substrate 104, hereby eliminating the need for transfer as well as removing the risk of cracks in the film 102.
• the disclosed 2DAC film consists of sp 2 -bonded carbon similar to glassy carbon; however the thickness is only approximately one atomic layer thick (6 A), thinner than any conventional reported amorphous carbon structure.
• FIG. 10 illustrates the X-ray photoelectron spectroscopy (XPS) measurement of 2D amorphous carbon on Cu, where the peak position indicates the sp 2 or sp 3 bonding type while the peak intensity indicates the fraction of each type of bonds. A mix concentration of C-C sp 2 and sp 3 bonding is also possible without sacrificing the thickness, though the maximum C-C sp 3 content is set to 20%.
• the thin structure and strong adhesion of the disclosed 2D AC intrinsically protects the underlying substrate all the time, unlike in thicker films where the possibility of flaking off is evident. 10
• a laser-based growth process using hydrocarbons as precursors (such as CH 4 , C 2 H 2 , etc.) produces the disclosed composite film.
• Hydrogen gas (H 2 ) and Argon gas (Ar) may also be mixed with the precursor.
• the laser has two roles: (1) an energy source to breakdown the precursor gas in a process called photolytic decomposition; and (2) as a local heat source. Assuming that one or both aforementioned roles produces the disclosed 2D AC film: in the first case, the substrate 104 is said to be at room temperature throughout the growth; in the second case, the laser can heat up the substrate 104 up to 500° C.
• a pulsed excimer UV laser (e.g., 193, 248 or 308 nm) can be directed onto or parallel to the substrate at a fluence from about 50 - 1000 mJ/cm 2 at different growth times, depending on the employed substrate.
• Other possible combinations to produce the disclosed composite may include utilizing any combination of a laser, plasma, and/or a substrate heater.
• a heater may be employed to heat the substrate 104 up to 500° C.
• Plasma power may be used in the range of and including 1 -100 W.
• a typical combination using hydrocarbon as precursor will be as follows: (i) Laser only; (ii) Laser + low power plasma (5W); (iii) Laser + low power plasma (5W) + heater (300° C - 500° C); (iv) Low power plasma (5W) + 500° C heater; (v) High power plasma (100W) only.
• the entire growth/deposition of the disclosed 2DAC and 2DAC composite may be performed within a chamber.
• Modules for heating, plasma, gas flow and pressure control may all be set and established within the chamber for the controlled growth environment.
• the process pressure of the chamber may be established in a range of, and including, 10 to 1E-4 mbar.
• the process parameters for the disclosed 2DAC may include the following: (i) process gas: CH 4 (ii) chamber pressure: 2.0 E-2 mbar; (iii) laser fluence: 70 mJ/cm 2 ; (iv) growth time: 1 min; (v) plasma power: 5W; (vi) substrate: Cu foil.
• a process for producing the disclosed 2D AC film may employ the use of methane (CH 4 ) within the growth chamber for the growth process.
• the gas pressure within the chamber during the growth is controlled at 2 E-2 mbar throughout. This gas is in the presence of a plasma generator operating at 5W power.
• the growth starts when the 248nm excimer laser is exposed on the surface of the copper foil substrate with a fluence of 70 mJ/cm 2 with a pulse frequency of 50 Hz.
• the laser exposure time i.e., growth duration
• the stage heater is not used.
• Multiple parameters disclosed herein may be adjusted, for controlling and/or changing the properties of the disclosed 2DAC including, but not limited to, hydrocarbons as precursors, precursor mixes, adjustments to the photolytic decomposition process and equipment, temperature regulations, substrate temperature adjustment, the change in C value, change in number of atomic layers, change in sp 2 to sp 3 ratio, and change in adhesion to substrate.
• the disclosed carbon film may be constructed with minimal thickness thereby ensuring that the disclosed metal surface of the substrate is consistently and completely covered during the lifetime of applied usage.
• the disclosed 2DAC thickness may be designed at approximately one atomic layer thick.
• the disclosed carbon film 102 may be grown directly on several substrates 104, for example, such as stainless steel and titanium materials. Since the growth is done at much lower temperature than, for example, graphene synthesis, the disclosed 2DAC may be grown directly to other substrates 104 that cannot withstand high temperature like glasses and hard discs. 11
• the disclosed 2DAC film 102 is ultra-strong and is strongly bounded to the substrate 104 making it suitable for applications that may require deformation such as bending and stretching.
• the strong mechanical properties of the disclosed 2DAC film is due to its lack of grain boundaries.
• the insulating property of the disclosed carbon film 102 prevents galvanic corrosion of the substrate 104 unlike graphene which enhances the corrosion.
• the 7-, 8-, and 9-membered rings of the carbon film, as seen in the TEM image, is useful as an efficient membrane for gases or for proton transport. 6
• the disclosed 2DAC may be generated as a free-standing case, for example, when a substrate is not suitable to be grown on, and hence the disclosed 2DAC needs to be transferred.
• Suitable methods and techniques for transferring the disclosed 2DAC 1202 may be employed such as dry transfer as described in the patent application: Defect-free direct dry delamination of cvd graphene using a polarized ferroelectric polymer WO2016126208A1.
• Other transfer methods may include, but not limited to, thermal release tape, pressure-sensitive adhesive, spin coating, spray coating, and Langmuir-Blodgett technique.
• the disclosed 2D AC may be directly grown on a substrate.
• Such benefits of the disclosed 2D AC film compared, for example, to graphene for the transfer process is that the disclosed 2DAC film does not require a sacrificial support layer for transfer (unlike graphene). With graphene, the film layer is required to prevent cracks and defects during the transfer, and the film layer needs to be removed after. Even with removal, there residues remain from the sacrificial layer that cannot be completely removed. With the disclosed 2DAC, the transfer can be done without the sacrificial layer, without inducing defects and without dealing with residues or compromising the structure.
• Advantages of the disclosed embodiments of the 2D AC layer may be implemented in a wide variety of applications including, but not limited to, an amorphous carbon overcoat layer employed in HAMR media technology, for example, as a protectant for an underlying magnetic recording layer.
• Such applications make use of the advantages of the disclosed 2DAC layer including, for example, an exemplary single layer of carbon atoms in a non crystalline structure having a C-value below or equal to 0.8.
• the continuous film of carbon is arranged in a random patterned that allows for an ultra-high transverse conductance of protons between approximately 0.1-10 S/cm 2 .
• Embodiments of the disclosed invention provide an overcoat layer protecting an underlying magnetic recording layer of a HAMR media.
• the overcoat layer may be employed as the disclosed 2D AC layer described above.
• FIG. 11 illustrates an exemplary a side cross section view of a HAMR recording device 1100, according to one disclosed embodiment. It is readily appreciated that the thickness of the exemplary HAMR device 1100 illustrating the disclosed layers is not necessarily to scale of an actual device.
• an overall construction of the HAMR device 1100 may include a substrate layer 1102, an adhesion layer 1104, a heat sink layer 1106, a soft under layer 1108, another under layer 1110, a recording layer 1112, a capping layer 1114, an overcoat layer 1116, and a lubricant layer 1118.
• Substrate layer 1102 may comprise glass, metallic substrates such as aluminum, or other base material such as an oxide of a material.
• An adhesion layer 1104 may be utilized, for example, to reduce delamination of top layers and improve flatness. 1,15
• a heat sink layer 1106 may be disposed on adhesion layer 1104 and is provided to dissipate heat such as from an employed laser, for example, during a HAMR operation.
• a soft under layer 1108, such as a soft magnetic layer, may be disposed, for example, over seat sink layer 1106 to provide a return path for the magnetic flux during operation.
• another under layer 1110 may be utilized, for example, being disposed over soft under layer 1108.
• Under layer 1110 may include a barrier layer and a seed layer and ordering temperature reducing layer in different arts.
• a recording layer 1112 may be disposed over under layer 1110.
• a capping layer 1114 may be employed and disposed over recording layer 1112.
• Capping layer 1114 utilizes magnetic material while providing protection to the recording layer.
• An overcoat layer 1116 such as the disclosed 2D AC layer described above, may be disposed over capping layer 1114.
• overcoat layer 1116 may be regarded as the disclosed 2D AC overcoat to provide anti-corrosion and anti-wearness protection.
• a lubricant layer 1118 may be employed over overcoat layer 1116 to reduce friction between the head and media surface to thereby reduce wear of the overcoat layer 1116.
• the overcoat layer 1116 of the disclosed invention may include a thickness of approximately one atom to a thickness of a few atoms.
• the aforementioned thickness range may include a thickness of approximately 0.2nm to about 2nm. The thickness range of the disclosed overcoat layer 1116 may significantly reduce the lower limits of the magnetic bit size.
• the overcoat layer 1116 of the present disclosure may consist of one atomic layer of carbon in one embodiment and few layers of carbon in another embodiment.
• the disclosed overcoat layer 1116 such as the 2DAC layer of the present disclosure, may be disposed over capping layer 1114.
• Overcoat layer 1116 is designed to provide improved adhesion properties to the applied surfaces while maintaining a low surface roughness. In some embodiments, the deposition of the overcoat layer 1116 on the recording surface roughness is less than 1A.
• the hard disk may contain all or some of the following layers: capping layer 1114, carbon overcoat layer 1116 and lubricant layer 1118.
• capping layer 1114 One main function of the aforementioned layers is to protect the hard disk from corrosion by the surrounding environment. This is especially true for magnetic hard disks subjected, for example, to HAMR techniques, where the magnetic hard disks experience thermal environments exposed to elevated temperatures.
• One of the main reasons that corrosion occurs is due to water molecules in the surrounding environment. Such water molecules promote galvanic corrosion.
• the conductivity of the common carbon overcoat also promotes the corrosion speed by providing the return path for electrons created by oxidization of the magnetic bits. Rough surface structure will worsen the corrosion due to the capillary retention of water from a humid environment.
• overcoat layer 1116 of the disclosed 2D AC possesses insulating properties.
• overcoat layer 1116 such as the disclosed 2D AC layer, is provided having a resistivity between approximately 10 2 -10 5 W-cm which facilitates the reduction in the galvanic corrosion effect.
• the water contact angle of overcoat layer 1116 is approximately 60, indicating a good hydrophobic surface (e.g., see FIG. 12).
• the hydrophobicity of the disclosed overcoat layer 1116 surface will help to reduce the formation of water menisci and, therefore, reduce attraction of water from the environment.
• the low roughness caused by the disclosed carbon overcoat layer 1116 will further reduce the corrosion and provides a stable storage for data.
• the carbon overcoat layer 1116 such as the disclosed 2D AC of the present disclosure, consists of more than 99% of carbon which are bonded together by C-C Sp 2 bond. There are less than 1% of O and H bonded to the carbon surface.
• the media surface of the HAMR media may experience fast local heating and cooling.
• a spot having a size less than 30 nanometers may be heated up to 400°C 12 within 5ns-200ns and then cooled down to room temperature.
• the ramping speed of the temperature may reach lO u K/s. 13, 14
• a conventional carbon overcoat contains both Sp3 and Sp2 bonding; due to the fast temperature ramping, the Sp3 bond between the carbon atoms will undergo a graphitization transformation during which, the Sp3 bond will transfer into an Sp2 bond and thus, case clustering and a discontinuous surface.
• overcoat layer 1116 such as the disclosed 2D AC contains an Sp2 carbon bond of more than 99%.
• the disclosed 2D AC is stable up to 700°C and annealing for over 2 hours. No bond change is obtained even under a high temperature ramp rate.
• disclosed embodiments of overcoat layer 1116, including the disclosed 2D AC may be subject to elevated working temperatures employed by HAMR media and provide thermal stability to coated surfaces while enhancing the anti-corrosion property of the same.
• FIG. 13 illustrates a diagram 1300 comparing the thermal stability between commercial carbon overcoat (CoC) 1302 with the overcoat layer 1116 of the present disclosure.
• the figure plots the change of the ratio ID/IG from the Raman mapping of both overcoats upon laser shining on the overcoat on hard disk.
• the commercial carbon overcoat 1302 experiences a sudden change in the I D /I G ratio which indicates graphitization.
• overcoat layer 1116 roughly maintains the same ratio indicating its superior thermal stability capability.
• Overcoat layers also utilized within a hard disk arrangement to provide a bumper like surface.
• the hard disk When the hard disk is in operation, there may exist contact-start-stop movement as when the slider starts to move. During the start and stop period, the read/write head will generally be in contact with the hard disk surface. Thus, a material with sufficient low friction is preferred to protect from excessive wear at the interface.
• Disclosed overcoat layer 1116 is designed to meet the tribology requirement to provide less friction and anti-weak surface. In one embodiment, overcoat layer 1116 includes a friction range of approximately 0.2-0.4 which is compatible to be utilized in place of current commercial carbon overcoat.
• FIG. 14 shows an exemplary cross sectional side view 1400 of a common head design for HAMR device.
• the magnetic recording bit 1402 is heated by a laser 1404 during a writing operation.
• the laser 1404 may be directed to the interface 1406 and pass through a near field transducer 1408 which facilities focusing light to a spot size approximately less than 30 nanometers.
• the laser 1404 is integrated to the head and it is preferably set to achieve the lowest possible laser power both for the purpose of saving energy and easier fabrication.
• Laser 1404 may be either UV, visible, or infrared light. In conventional arrangements, before reaching the magnetic bit, laser 1404 will generally go through lubricant layer 1118 and overcoat layer 1116. Generally, energy loss occurs due to the reflection of the layers.
• the reflectance of the light is about 65% for light with wave number around 2000cm 1 (US 8760980 B2).
• the present disclosure provides a carbon overcoat layer 1116 with a reflection less than 5%, for example, in the ultraviolet (UV) region and even less in other region as shown in chart 1500 of FIG. 15.
• UV ultraviolet
• the disclosed overcoat layer 1116 such as 2D AC, possesses a high out-of-plan thermal conductivity property while also possessing a lower lateral thermal conductivity property.
• the vertical conductivity property of the disclosed 2DAC increases the thermal coupling between overcoat layer 1116 and the magnetic layer and also increases the heating efficiency.
• the low lateral thermal conductivity property of the disclosed 2D AC confines the heating locally and allows overcoat layer 1116 to achieve higher temperature gradients within a small thermal spot.
• amorphous materials disclosed by present embodiments contain fundamental properties that may be regarded as possessing great practical importance.
• a basic framework of understanding even from a theoretical point of view, is still missing from conventional dialogue and comprehension.
• the disclosed invention not only contemplates but demonstrates the synthesis of a freestanding, continuous and air stable, monolayer of amorphous carbon (MAC) by laser-assisted chemical vapor deposition.
• 17 Atomic scale TEM imaging reveals a fully sp 2 structure, with a wide distribution in both the bond length and angle with a complete lack of any long-range periodicity.
• the absence of crystallinity leads to an Anderson insulating phase with both tunneling and sheet resistance values similar to h-BN.
• the flexibility of the disclosed carbon film strongly increases without compromising its breaking strength.
• Disclosed embodiments demonstrate, for the first time, the synthesis of free-standing MAC and provides crucial insights into its formation, atomic structure and physical properties. This opens up the possibility to realize wider range applications with atomically thin amorphous films, which neither can be realized with 2D crystalline materials nor with 3D amorphous materials. Examples range from heat-assisted magnetic recording (HAMR) to as a proton barrier material and even for stem cell research.
• HAMR heat-assisted magnetic recording
• a laser-assisted chemical vapor deposition (CVD) growth process is developed for MAC.
• the process works on arbitrary substrates. It results in a complete film coverage in under 30 seconds and at substrate temperatures as low as 200°C. Since the laser is the sole heat source, both the process duration and temperature may be adjusted, as needed, such as for further refinement.
• Such disclosed films can be easily transferred from its growth substrate without sacrificing stability.
• disclosed embodiments discuss representative data mainly on MAC films grown on a copper foil unless otherwise stated.
• PG graphene
• PG h-Bn
• FIGS. l6a and b illustrate the transferred sample on both Si0 2 /Si wafer and TEM grid, respectively, to be homogenous and continuous. Specifically, FIG. l6a is a graphical illustration of a monolayer of amorphous carbon (MAC) transferred onto a Si0 2 /Si wafer. FIG. l6b is a graphical illustration of an SEM image of a MAC suspended on a TEM grid with 2.5 pm diameter holes. There is no evidence of multilayer regions or wrinkles that are typically observed with the transfer of 2D layers.
• MAC amorphous carbon
• FIG. l6c illustrates Raman spectra of the amorphous carbon grown on different substrates, with the measurements for Cu and Au done on films transferred to Si0 2 , while directly measured on Ru.
• FIG. l6d illustrates Raman spectra for Cu growth showing the D and G bands with fitted curve and an I(D)/I(G) ratio of 0.82.
• FIG. l6e is a graphical illustration of Cls XPS spectra measured directly on different substrates.
• FIG. l6f is a graphical illustration of high
• FIG. 17 is directed to the morphology of the disclosed monolayer amorphous carbon.
• FIG. l7a is a monochromated HRTEM image of the disclosed amorphous carbon monolayer. The sample is imaged at 700°C in order to eliminate any carbon redeposition. Due to the reduced chromatic aberration, each carbon atom can be clearly seen in the image.
• FIG. l7b illustrates a large scale atom-by-atom mapping of the selected region in FIG. l7a. Pentagons, octagons and strained hexagons are omnipresent. The contrast of the image is inverted and false colored for better visibility.
• FIG. 17 is directed to the morphology of the disclosed monolayer amorphous carbon.
• FIG. l7a is a monochromated HRTEM image of the disclosed amorphous carbon monolayer. The sample is imaged at 700°C in order to eliminate any carbon redeposition. Due to the reduced chromatic aberration, each carbon atom can be clearly seen in the image.
• FIG. l7c illustrates a zoom-in region highlighted by the outlined red square in FIG. l7b.
• the pentagons, octagons and strained hexagons are colored as red, blue and green, respectively.
• the bond length and bond angle of each pentagon is precisely measured, indicating a wide variety of distribution in both the bond length and angle, a disorder feature in monolayer.
• FIG. l7d illustrates a pair correlation function calculated by the mapping coordinate of each carbon atom. Graphene imaged under similar condition and the same mapping algorithm is shown as a reference.
• FIG. l7e illustates the comparison of the bond length distribution for the first neighboring atoms between graphene and the disclosed amorphous carbon monolayer.
• FIG. l7f illustrates a statistical histogram of bond angle distribution between MAC and graphene.
• the disclosed HRTEM image reveals the presence of connected hexagonal and non-hexagonal structures in a form of 5-, 7-, and 8-membered rings (FIGS. l7a-c).
• the observed lattice disorders are randomly distributed; a stark contrast exists to point to defects in defected graphene, or grain boundaries at the interface between crystals. 21
• direct imaging of amorphous structure was not possible, as 2D amorphous did not exist until recently. Not much was known about the composition of the amorphous network, and a quantitative measure of amorphousity should be adopted as a standard reference. Lichtenstein, et al. recently defined crystallinity (or“amorphousity”) of a sample as the ratio of the total number of hexagons, N 6 , over the total polygons 22 ;
• Disclosed embodiments investigated the mechanical properties of such suspended MAC membranes in more detail by indentation experiments using atomic force microscopy (AFM) with diamond tips.
• MAC breaks when indentation force is approximately 200 nN, similar to PG, and approximately one order of magnitude lower fracture load than single crystalline graphene (SG) or h-bN 25 .
• FIG. l8a illustrates a force vs. deflection curve and curve fitting to Equation (2) for the calculation of E 2 D and pre-tension values.
• the left inset is an AFM scan of MAC suspended on a 2.5 pm diameter well.
• the cyan line is the height profile along the center with 10.0 nm adhesion depth to well wall. Scale bar, lpm.
• the right inset illustrates an indentation fracture at the center of MAC.
• the cyan line is the height profile along the center. Image width, 500 nm. It is immediately clear that the indentation rupture is restricted and does not propagate (FIG. 18a).
• FIG. l8b illustrates a histogram of the 2D elastic stiffness of an exemplary 39 membranes studied.
• E 2 D pre-tension and 2D elastic stiffness
• FIG. l8c shows graph illustrating a 2D elastic modulus vs. pre-tension with linear fit (red line) and theoretical range (blue band).
• the resulting non-linear but fully reversible E 2D increases in stiffness with increasing pre-tension (FIG. l8c), which is typical of a polymer network rather than a continuous sheet.
• the disclosed MAC changes from a soft to hard material with stretching, and points towards unstretched MAC being much more flexible than graphene.
• FIG. l8d the top illustration shows a theoretical simulation of out-of-plane structural relaxation increases monolayer thickness from in-plane thickness of 3.4 A.
• the bottom portion of FIG. l8d illustrates AFM images of 1-3 layers of MAC on Si02/Si.
• the cyan dash line indicates line scan position for overlaid height profile.
• the inset Image width, 3 pm. From these measurements, a step height of 0.6 nm was measured (FIG. l8d).
• the step height of a single MAC layer was measured on atomically flat hexagonal Boron Nitride (h-BN) surface to be 0.58 nm step height.
• h-BN hexagonal Boron Nitride
• the step heights of MAC grown on other surfaces are similar.
• MAC grown on gold is approximately 0.6 nm thick (details in SI).
• FIG. l8e illustrates a theoretical model used for simulations in accordance with disclosed embodiments.
• DOS density of states
• FIG. 19a provides a SEM image of the two-terminal device with 2()0nm-lpm channel width between a 50 pm long electrodes.
• the inset is a close up of MAC/S1O2 edge in a 1pm channel.
• the ease of transfer to and stability on insulating substrates allows disclosed embodiments to carefully study both its optical properties and transport properties (FIG. l9a). Optical measurements are first examined according to disclosed embodiments.
• FIG. l9b illustrates optical transmittance of 2D amorphous carbon measured by transferring the film on a quartz substrate.
• the dashed line indicates pristine graphene absorption at 2.3%.
• the inset represents a Tauc plot to determine the optical bandgap in amorphous materials, with extrapolation of the linear region (red line) estimating an optical band gap of 2.1 eV.
• the optical transmittance of MAC was measured to be 98.1% at 550 nm wavelength, higher than the intrinsic 97.7% transmittance of graphene (FIG. l9b). More importantly, the Tauc plot gives an optical band gap of 2.1 eV, well within the range of the predicted values.
• the plot has a long tail towards lower energies, which confirm a wide energy distribution of localized states.
• Disclosed embodiments also observe a Photoluminescence (PL) signal from MAC with a pronounced PL peak at 2.04eV. Both are in agreement with localization effect.
• PL Photoluminescence
• a method for large area growth of freestanding monolayer of sp2 amorphous carbon film is shown.
• This is the first example of an amorphous material in the 2D limit. It can be grown directly on a wide range of surfaces at low temperatures making it a more enticing than crystalline 2D materials for many device applications. Examples may range from anti-oxidation coating on magnetic hard disc for heat assisted magnetic recording to coatings on current collector electrodes in batteries.
• direct growth on e.g., glass well plates would make it very practical for biomedical research, e.g., stem cell research.
• the insulting behavior also make it an attractive 2D dielectric for FET, spin dependent tunneling barrier in magnetic tunneling junctions and even for use in electronic synapses. Its higher mechanical stability under strain make it also promising for nanopore type of applications. Last but not least, the insulating behavior in conjunction with the high the large carbon rings make it an even more promising 2D material for proton membrane applications than graphene itself. Generally speaking, many applications for 2D materials require direct growth on specific target substrates or on top of devices, better mechanical flexibility and insulating behavior. The disclosed MAC provides an appealing alternative for these applications.
• the system may be embodied in the form of data storage media, for example, for a computer system.
• Typical examples of a computer system includes a general-purpose computer, a programmed micro processor, a micro-controller, a peripheral integrated circuit element, and other devices or arrangements of devices that are capable of implementing the steps that constitute the method of the present technique.
• the computer system comprises a computer, an input device, a display unit and/or the Internet.
• the computer further comprises a microprocessor.
• the microprocessor is connected to a communication bus.
• the computer also includes a memory.
• the memory may include Random Access Memory (RAM) and Read Only Memory (ROM).
• the computer system further comprises a storage device.
• the storage device can be a hard disk drive or a removable storage drive such as a floppy disk drive, optical disk drive, etc.
• the storage device can also be other similar means for loading computer programs or other instructions into the computer system.
• the computer system also includes a communication unit.
• the communication unit allows the computer to connect to other databases and the Internet through an EO interface.
• the communication unit allows the transfer as well as reception of data from other databases.
• the communication unit may include a modem, an Ethernet card, or any similar device which enables the computer system to connect to databases and networks such as LAN, MAN, WAN and the Internet.
• the computer system facilitates inputs from a user through input device, accessible to the system through I/O interface.
• the computer system executes a set of instructions that are stored in one or more storage elements, in order to process input data.
• the storage elements may also hold data or other information as desired.
• the storage element may be in the form of an information source or a physical memory element present in the processing machine.
• the set of instructions may include various commands that instruct the processing machine to perform specific tasks such as the steps that constitute the method of the present technique.
• the set of instructions may be in the form of a software program.
• the software may be in the form of a collection of separate programs, a program module with a larger program or a portion of a program module, as in the present technique.
• the software may also include modular programming in the form of object-oriented programming.
• the processing of input data by the processing machine may be in response to user commands, results of previous processing or a request made by another processing machine.

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