Graphene and its derivatives for Nanoscale Semiconductor Memories

Abstract—Memory occupies large portion of
semiconductor industry.A lot of researches are going on about new memory
materials.In this paper we explore electronic,optical and mag-netic properties
of graphene and graphene nanoribbons for semiconductor memory applications.Graphene
is having high mobility,good scaling properties.Also it shows Ferromagnetic and
anti ferromagnetic properties.Measurable Optical properties are appeared in
literature. All these properties are tunable with band gap .These factors point
outs that graphene is a suitable candidate for making memories like
flash,optical storage devices,Magnetic RAM etc.The bandgap of the graphene is a
considerable design problem when making electronic devices.But nanoribbons can
solve this issue and can provide enough band gap suitable for memory
devices.Short channel effects scattering,ambipolar conduction is another point
that need attention

 

Keywords—Graphene,AGNR,ZGNR,Bandgap,Spin
Polarisation.

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I.    
INTRODUCTION

 

According to ITRS, Memory technology is
always the drivers of moore’s law.But DRAM and flash memory are reaching its
limit and by 2024 it will saturate .This indicates the need for new materials
and methods.3D architecture is proposed as an alternative technology for
scaling, but still this faces reliability issues like cell to cell
interference, endurance and retention.ECC schemes, wear leveling ,memory
scrubbing etc were used to overcome this issues but all these again leads to
higher area conception. Hewlett Packard is doing research on a memory device
that uses nanowires coated with titanium dioxide to form memoristor.And also
they are working with Hynix Semiconductor to develop Resistive Random Access
Memory (ReRAM).Researchers at IBM have developed race track memory by
magnetizing sections of nanowires. Researchers at Rice University have found
that they can use silicon dioxidenanowires sand witched between two electrodes
to create memory devices. Another method has been developed to increase the
density of memory devices is to store information on magnetic nanoparticles.
Researchers at North Carolina State University were found growing arrays of
magnetic nanoparticles, called nanodots, which are about 6 nm in diameter.
Intel and Micron have announced 3D XPoint, which is 1,000 times quicker and
1,000 times more durable than existing NAND flash. It also offers a 10x
improvement in density. It uses bulk material property change.

 

Graphene has drawn
attention of researchers because of its

 

 

Dr.N.M Sivamangai

 

Department of electrical Technology Karunya
Institute of Engineering and Technology

 

Coimbatore, India-641 114

 

Email:[email protected]

 

 

electronic properties and hence One of the candidate for post
silicon era.In this paper we like to present graphene and its variants for
different kinds of storage device solutions.Section II discuss the graphene
prospectus.SectionIII presents GN-RFET based memory.Section IV presents
magnetic memory using graphene.Section V describe about optical properties of
graphene for optical memories. Section VI discusses Resistive memory the
graphene.

 

II.     
GRAPHENE PROSPECTUS

 

A paper published on 2004 [2], [3] about
graphene opened a lot of discussion about its electronics properties.Earlier
dis-cussions was about the mobility of graphene [2]The measured record
mobility’s in graphene will be more than 100 000 cm2/Vs at room temperature and
1 000 000 cm2/Vs at 4 K [4], [5].Since high mobilities leads to high
performance devices ,this opened the thought of device engineers.

 

The main category of graphene are a)large
area graphene b)Bilayer graphene c)Graphene nanoribbons.Among this large area
graphene and bilayer graphene are having bandgap problems and showing ambipolar
conduction.But graphene nanoribbon showing excellent tunable bandgaps.There is
two variants of graphene nanoribbon Zigzag and Armchair .In this Zigzag
graphene nanoribbon(ZGNR) is metallic in nature where as Armchair
graphene(AGNR) shows enough band gaps as shown in Fig2

 

All these observations lead to the idea of bandgap engineering in
graphene.Raman spectroscopy studies reveal that by con-trolling
width,dopping,strain bandgap can be improved[6].

Graphene oxide,because of its flexibility draws attention for
making flexible devices.Later it was proved that GO is having good electronics
properties.The same way quantum dots of graphene can be used for improving
electronics performance.[11]

 

III.      
TRANSISTOR BASED MEMORY

 

Graphene can be
used as channel material for normal FET in order to improve the performance.In
memory applications the main scenario is ON/OFF ratio.The second one is
sub-threshold conduction.scaling and short channel effects.With the inherent
properties of graphene,all these can be improved. when studying the bandgap ,it
is already observed that bilayer suitable for memory application.Experimentally
proved that at least 300 to 400mev band gap is required for memory