Graphene(field,effect(transistors( - PowerPoint PPT Presentation

Graphene(field,effect(transistors( A(realis4c(alterna4ve(to(Si(based( technology?( ( ( ( ( ( Talk(by(Niclas(Müller( 1(

1.(Introduc4on(and(Mo4va4on( Proper4es(of(field,effect(transistor(and(market(development( Important(proper4es(of(FET:( ( • Gate(length( • On/Off,ra4o( (( • Transconductance,(carrier(mobility(( Graphene(field,effect(transistors( 2( Pictures(from: (F.(Schwierz,(Nature(Nanotechnology(5,(2010 ( ((

Structure(of(the(talk( • Discovery(of(graphene( ( ( • (Electronic(proper4es(of(graphene( ( ( ( • (Graphene(FETs(for(high(frequency(applica4ons( ( ( ( • (Graphene(FETs(for(digital(logic(devices( Graphene(field,effect(transistors( 3(

2.(Discovery(of(graphene( Reduc4on(of(graphene(oxide(by(Boehm(et(al.(in(1962( Graphite(oxide(is(hydropilic(and(forms(( • monolyer(flakes(in(water( • (Reduc4on(with(hydrazine(hydrate(to(((( ((((((graphene( Graphene(field,effect(transistors( 4( Pictures(from: (Boehm(et(al.,(Anorg.(Allg.(Chem.(316,(1962( ( (Boehm(et(al.,(Carbon(24,(1986( ( ( (

2.(Discovery(of(graphene( Produc4on(of(graphene(by(micromechanical(cleavage(2004( 8Å( 1μm( Micromechanical(cleavage(of(graphene( • from(graphite( • Iden4fica4on(of(some(flakes(as( monolayer( ( Making(graphene(visible(by(naked(eye( • on(Si+300nm(SiO 2 ( Graphene(field,effect(transistors( 5( Pictures(from: (Novoselov(et(al.,(Science(306,(2004( ((((((((((( (Novoselov(et(al.,(Appl.(Phys.(Lea.(91,(2007((( (

2.(Discovery(of(graphene( Electrical(field(effect(in(graphene(2004( Graphene(field,effect(transistors( 6( Pictures(from: (Novoselov(et(al.,(Science(306,(2004( ( ((

3.(Electronic(proper4es(of(graphene( Bandstructure(and(ladce( Tight,binding(hamiltonian:( + b j , σ + a j , σ ) ∑ H = − t ( a i , σ + b i , σ i , j , σ + a j , σ + b j , σ ) ∑ − # t ( a i , σ + b i , σ i ≠ j , σ Derived(energy(bands:( E ( k x , k y ) = ± t 3 + f ( k x , k y ) + ! t ⋅ f ( k x , k y ) with( ( ) f ( k x , k y ) = 2cos 3 k y a ! $ ! $ 3 & cos 3 + 4cos 2 k y a = 2 k x a # # & " % " % Graphene(field,effect(transistors( 7( Pictures(from:(Castro(Neto(et(al.,(Rev.(Mod.(Phys(81,(2009( ( ((

3.(Electronic(proper4es(of(graphene( Bandstructure(and(charge,carrier(veloci4es( • Approxima4on(at(K,point:( E ± (   q) = ±  v F q with(Fermi(velocity(independent( of(mass(and(energy( ( ( v F = 3 ta / 2  ≈ 10 6 m / s ≈ c / 300 • Compare(with(photon(dispersion( rela4on:( E (  q) =  c  q • Electrons(have(to(be(described( as(massless(rela4vis4c(par4cles( by(Dirac(equa4on( ((( Graphene(field,effect(transistors( 8( Pictures(from:( (Castro(Neto(et(al.,(Rev.(Mod.(Phys.(81,(2009( ( (J.(Hicks,(E.H.(Corad,(MRS(Bulle4n(37,(2012( ( ((

3.(Electronic(proper4es(of(graphene( Bandstructure(and(charge,carrier(veloci4es( • Approxima4on(at(K,point:( E ± (   q) = ±  v F q with(Fermi(velocity(independent( of(mass(and(energy( ( ( v F = 3 ta / 2  ≈ 10 6 m / s ≈ c / 300 • Density(of(states:( Graphene(field,effect(transistors( 9( Pictures(from:( (Castro(Neto(et(al.,(Rev.(Mod.(Phys.(81,(2009( ( ( ( ((

3.(Electronic(proper4es(of(graphene( Charge,carrier(mobility( • Charge,carrier(mobility(μ(=(How(quickly(can(charge,carrier(move,(when(pulled( by(an(electric(field(E( v D = µ ⋅ E • Determine(carrier(density(by( applying(magne4c(field:( B n ( V G ) = e ⋅ ρ 26 ( V G , B ) • Measure(carrier(mobility:( 1 µ ( n ) = ne ρ 23 • Highest(value(measured:( µ max = 230.000 cm 2 / Vs Graphene(field,effect(transistors( 10( Pictures(from:( (Bolo4n(et(al.,(Solid(State(Comm.(146,(2008 ( ((

3.(Electronic(proper4es(of(graphene( Charge,carrier(mobility( • Charge,carrier(mobility(μ(=(How(quickly(can(charge,carrier(move,(when(pulled( by(an(electric(field(E( v D = µ ⋅ E Other(materials:( • Determine(carrier(density(by( 3.000.000 cm 2 / Vs • 2DEG( applying(magne4c(field:( 100.000 cm 2 / Vs • Carbon(Nanotubes(( 78.000 cm 2 / Vs • IrSb( B n ( V G ) = 9.200 cm 2 / Vs • GaAs( e ⋅ ρ 26 ( V G , B ) 3.900 cm 2 / Vs • Ge( 1.400 cm 2 / Vs • Measure(carrier(mobility:( • Si( 1 µ ( n ) = ne ρ 23 • Highest(value(measured:( µ max = 230.000 cm 2 / Vs Graphene(field,effect(transistors( 11(

3.(GFETs(for(RF,applica4ons( Characteris4cs(of(graphene(field,effect(transistors((GFETs)( Graphene(field,effect(transistors( 12( Pictures(from:( (P.(Avouris(and(F.(Xia,(MRS(Bulle4n(37,(2012 ( ((

3.(GFETs(for(RF,applica4ons( Top,gated(GFETs( Graphene(field,effect(transistors( 13(

3.(GFETs(for(RF,applica4ons( Top,gated(GFETs( Graphene(field,effect(transistors( 14(

3.(GFETs(for(RF,applica4ons( Top,gated(GFETs( Graphene(field,effect(transistors( 15(

3.(GFETs(for(RF,applica4ons( Problems:(Metal,graphene(contacts( Effect(of(palladium(contacts(on(GFET( characteris4cs,(because(of(p,doping.( ( ! Forma4on(of(p,n,p(structure(in( graphene( ! Effect(stronger(with(decreasing(channel( length(( Graphene(field,effect(transistors( 16( Pictures(from:( (P.(Avouris(and(F.(Xia,(MRS(Bulle4n(37,(2012 ( ((

3.(GFETs(for(RF,applica4ons( Problems:(Gate(dielectrics(and(substrate( • Very(thin,(highly,dielectric(film(needed( • Graphene(is(chemically(inert(and( hydrophobic( ! insula4ng(materials(form(poor, ( (quality,(nonuniform(and(leaky(( ( (films((e.g.(SiO 2 ,(HfO 2 ,(Al 2 O 3 )( ( ! charges(trapped(at(graphene, ( ( (insulator(interface( ( ! drama4c(decrease(of(carrier( ( ( (mobility( Graphene(field,effect(transistors( 17(

3.(GFETs(for(RF,applica4ons( Problems:(Gate(dielectrics(and(substrate( ( • Suitable(insulators:(Diamond,like(carbon,( ( ( ( ( ((h,BN( ! Carrier(mobili4es((for(h,BN)( > 100.000 cm 2 / Vs (( ( ( ! Scaaering(mean(free(path(( ( ((for(h,BN)( ≅ 1 µ m Graphene(field,effect(transistors( 18(

3.(GFETs(for(RF,applica4ons( State(of(the(art( Graphene(field,effect(transistors( 19( Pictures(from:( (P.(Avouris(and(F.(Xia,(MRS(Bulle4n(37,(2012 ( ((

3.(GFETs(for(RF,applica4ons( State(of(the(art( Graphene(field,effect(transistors( 20( Picture(adapted(from:(( (F.(Schwierz,(Nature(Nanotech,( ( ( (nology(5,(2010( ( ((

3.(GFETs(for(RF,applica4ons( State(of(the(art( Graphene(field,effect(transistors( 21( Pictures(from:(( (F.(Schwierz,(Nature(Nanotechnology(5,(2010( ( (L.(Liao(and(X.(Duan,(Materials(Today(15,(2012( ( ((

4.(GFETs(for(digital(logic(devices( Opening(a(Band(gap:(AB,stacked(Bilayer(Graphene( • Band(gap,(which(depends(on(electric( field( ( • Parabolic(bandstructure(( ( ! No(more(rela4vis4c(behavior(of(( ( (electrons( ( ! Lower(carrier(mobili4es(( Graphene(field,effect(transistors( 22( Pictures(from:(( (D.(Reddy(et(al.,(J.(Phys.:( ( (Appl.(Phys(D.(44,(2011 ( ((

4.(GFETs(for(digital(logic(devices( Opening(a(Band(gap:(AB,stacked(Bilayer(Graphene( • Molecules(are(used(to(dope(graphene(and(generate(electrical(field( • On,Off(ra4os(up(to(70( Graphene(field,effect(transistors( 23( Pictures(from:(( (Zhang(et(al.,(ACS(Nano(9,(2011( (

4.(GFETs(for(digital(logic(devices( Opening(a(Band(gap:(Graphene(nanoribbons( Zigzag(GNR( Armchair(GNR( semiconduc4ng( metallic( Graphene(field,effect(transistors( 24( Pictures(from:(( (L.P.(Biro(et(al.,(Nanoscale(4,(2012( (

4.(GFETs(for(digital(logic(devices( Opening(a(Band(gap:(Graphene(nanoribbons( ZigZag(GNR( Armchair(GNR( (Band(gap(inversly(propor4onal(( ((((( (to(width(of(GNR( Graphene(field,effect(transistors( 25( Pictures(from:(( (L.P.(Biro(et(al.,(Nanoscale(4,(2012( ( (Huang(et(al.,(Mat.(Science(and(Eng.(70,(2010( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Produc4on(methods( Unzipping(of(carbon(nanotubes( Graphene(field,effect(transistors( 26( Pictures(from:(( (Kosynkin(et(al.,(Nature(Leaers(458,(2009( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Produc4on(methods( Unzipping(of(carbon(nanotubes( • Width(of(10,20nm ( • Carrier(mobility(of( 1.500 cm 2 / Vs ( • Nanoribbon(yield(of(2%(( Graphene(field,effect(transistors( 27( Pictures(from:((L.(Jiao(et(al.,(Nature(Nanotechnology(5,(2010( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Produc4on(methods( Nanowire(mask( • Silicon(nanowires(as(mask( • Width(below(10nm ( • Controllable(diameter( 23nm ( 31nm ( 14nm ( 9nm ( 6nm ( Graphene(field,effect(transistors( 28( Pictures(from:((J.(Bai(et(al.,(Nano(Leaers(9,(2009( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Produc4on(methods( • Chemically(derived( • On/Off,ra4os(up( (((((to(10.000.000 ( • Width(below(10nm( • Bandgaps(up(to((( (((((400meV( ( Carrier(mobili4es(( • 200 cm 2 / Vs ((((((of(( ( All(GNR(produced( • ((((((have(band,gap( Graphene(field,effect(transistors( 29( Pictures(from:((Li(et(al.,(Science(319,(2008( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Nanomeshes( Graphene(field,effect(transistors( 30( Pictures(from:((J.(Bai(et(al.,(Nature(Nanotechnology(5,(2010( (

4.(GFETs(for(digital(logic(devices( Graphene(nanoribbons(–(Nanomeshes( 100nm( 100nm( 500nm( Graphene(field,effect(transistors( 31( Pictures(from:((J.(Bai(et(al.,(Nature(Nanotechnology(5,(2010( (