4 AlGaN/GaN HEMT
AlGaN/GaN HEMT.6 7 cm/s 3.4 ev 3 6 V/cm FET AlGaN/GaN HEMT FET FET FET ( ). V -8 V ( ) SiO FET SiO FET SiO FET SiO AlGaN 4 cm -.5 ev.5 ev Id-Vg..5 ev( ) Id-Vg ( 3).5,. ev AlGaN Id-Vg SiO/AlGaN OFF SiO AlGaN/GaN HEMT (a) 4 (b) SiO 3 V ds =.V DEG GaN FET (a) (b) I d [ A] SiO SiO 5 V g [V] Id-Vg I d [ A] 5 E T =.5eV.eV Metal Gate..5eV 8 6 4 V g [V] 3
FET FET FET FET I-V FET I-V
C-V TLM 3
947 948 John Bardeen Walter Brattain Point-Contact Transistor William Shockley [] (Si) [] Si 7 cm/s (GaAs) (InP) (GaN) (SiGe) InP HEMT(High Electron Mobility Transistor) (f T ) 5GHz SiGe HBT(Heterojunction Bipolar Transistor) 35GHz Si MOSFET(Metal Oxide Semiconductor Field Effect Transistor).3 m 5mV Si nm GaN Si Si Si [3] 993 MESFET(Metal Semiconductor Field Effect Transistor) M. Asif Khan [4] AlGaN/GaN HEMT [5].6 7 cm/s GaAs. m GHz [6] 3.4eV 3 6 V/cm 3W 3.5W/mm [7] 4
3 IMT International Mobile Telecommunication GHz LAN Local Area Network Bluetooth.4GHz IEEE8.a 5GHz FWA( 6GHz Gbps FET [8] [9] [] AlGaN/GaN HEMT FET 3 FET 4 FET AlGaN/GaN HEMT / 5 4 6 5
[] Si NSS(E)[cm - ev - ] FET OFF [] [] [3] Si GaAs 6
GaN (ET) ( ) (NT) DLTS(Deep Level Transient Spectroscopy) C-V(Capacitance-Voltage) XPS(X-ray Photoelectron Spectroscopy) DLTS MIS(Metal Insulator Semiconductor) C-V MIS C-V C-V XPS X FET 7
FET FET AlGaN/GaN HEMT 3. 3. 33 m MOCVD(Metal-Organic Chemical Vapor Deposition) GaN m 6,3% AlGaN 3nm A A B B 3. RIE(Reactive Ion Etching) Ti/Al /nm 65 SiO 6nm Ni/Au 5/6nm 3. A B [ m] [cm -3 ] [ m] [cm -3 ] Undoped-AlGaN Al=.6.3 Al=.3.5 Undoped-GaN 33 33 8
RIE) 6nm Ti/Al /nm) N,65 min 3. SiO 6nm) Ni/Au 5/6nm) 3. 9
(SiO) (a) MES (b) MIS 3.3 4 m MESFET MISFET 3.3 5 m 4 m Id-Vd 3.4 3.4 A,B MES MIS A gd 5V 5 V Id-Vg 3.5 3.5 A,B MIS MES SiO MIS SiO MES SiO 5 6pF (gm)
V g : to 8V, V step V g : to 8V, V step 5 (a) 5 (b) I d [ma] I d [ma] 5 5 5 5 V d [V] V g : to 8V, V step 5 V d [V] V g : to 8V, V step 5 5 (c) 5 (d) I d [ma] I d [ma] 5 5 5 5 V d [V] 5 V d [V] 5 3.4 Id-Vd (a) A MES (b) A MIS (c) B MES (d) B MIS g m µ WC i = Vd (3.) L g m µ WCi = ( Vg VT ) L (3.) (gm: : W: L: Ci: Vd: Vg: VT: )
3.6 3.6 MIS khz gm SiO 5.6 9 cm AlGaN ev AlGaN 6 3 cm 3.7 A 4cm /Vs B 4cm /Vs I d [A] 3 4 (a) I d g m V d =V V d =V V d =.V 5 g m [ms/mm] I d [A] 3 4 (b) I d g m V d =V V d =V V d =.V 5 g m [ms/mm] 5 5 V d =.V 6 5 V g [V] V d =.V 6 5 V g [V] I d g m V d =V I d g m V d =V I d [A] 3 4 (c) V d =.V 5 g m [ms/mm] I d [A] 3 4 (d) V d =.V 5 g m [ms/mm] 5 V d =V 5 V d =V 6 V d =.V 5 V g [V] 6 V d =.V 5 V g [V] 3.5 Id-Vg (a) A MES (b) A MIS (c) B MES (d) B MIS
L g =4 m W g =5 m V d =V, V g = 4V.5 STDFET g m [ms].5 MISFET 4 6 Frequency [Hz] 3.6 B C-V 3.8 A 6 B 6 C-V 3.9 A,B AlGaN/GaN cm -3 nm 6 cm -3 AlGaN/GaN 3 (a) 3 (b) Mobility [cm /Vs] Mobility [cm /Vs] 8 6 4 V g [V] 8 6 4 V g [V] 3.7 (a) (b) A B 3
Capacitance [pf] 8 6 4 (a) 6 6 Phase [degree] Capacitance [pf] 8 6 4 (b) 6 6 Phase [degree] 8 6 4 Voltage [V] 3.8 C-V (a) A (b) B 8 6 4 Voltage [V] GaN (RC) TLM(Transmission Line Model) ( 3 ) 3. 3. A (RS) 464 /.38 mm B.6 3 / 35. mm (a) (b) Carrier Conc. [cm 3 ] 8 6 Carrier Conc. [cm 3 ] 8 6 4 4 6 Depth [nm] 4 4 6 Depth [nm] 3.9 (a) A (b) B 4
5 Rs=464 [ ] Rc=.38[ mm] 6 Rs=.6 3 [ ] Rc=35. [ mm] Resistance [ ] 5 R=R s /W L+R c /W Resistance [ ] 8 4 R=R s /W L+R c /W (a) 3 4 Length [ m] (b) 3 4 Length [ m] 3. TLM (a) A (b) B 5
FET XPS MISFET C-V Terman FET FET FET FET 4. FET FET m m 4 m FET SiO FET SiO FET (a) (b) SiO DEG GaN 4. FET (a) (b) 6
FET I-V A,B Id-Vd 4. MES ( 4.(a),(d)) A,B FET ( 4.(b),(e)) FET ( 4.(c),(f)) A Id-Vd B FET Id-Vg 4.3 A MES Id-Vg FET SiO SiO B MES SiO FET A SiO FET A SiO gm FET (gm) g m µ WCiVd = (4.) L ( : W: Ci: Vd: L: ) SiO FET SiO FET g mwp W wp = Wnp (4.) g mnp 7
Vg : to 8V, V step (a) V g : to V, V step (d) I d [ma] I d [ma] 5 5 V d [V] 5 V d [V] 5 V g : to V, V step (b) (e) I d [ma] I d [ma] V g : to 8V, V step 5 5 V d [V] 5 V d [V] 5 V g : to 8V, V step V g : to V, V step (c) (f) I d [ma] I d [ma] 5 5 V d [V] 5 5 V d [V] 4. FET Id-Vd (a) A MES (b) A (c) A (d) B MES (e) B (f) B (Wwp:SiO Wnp:SiO gmwp:sio 8
4 V ds =.V 4 V ds =.V 3 (a) 3 (b) I d [ A] SiO SiO 5 V g [V] I d [ A] SiO SiO 5 5 V g [V] 4.3 FET Id-Vg (a) A (b) B gmnp:sio ) (4.) Wnp=6 m gmwp=.6-6 S gmnp=5. -7 S Wwp=.7 m ~7 m A,B SiO/AlGaN [] Shockley-Read-Hall(SRH) f T dft dt = nc f ) e f pc f + e ( f ) (4.3) n ( T n T p T p T (t: n: p: Cn: Cp: en: ep: ) 9
(4.3) df T /dt= f T f T ncn + pc p = (4.4) C n + n ) + C ( p + p ) n ( p 4 f T (Efn) (Efp) 4...5eV f T 4.4(a) (e) 4. f T (Eg) 3.4 [ev] (me).8 (mp).6 (NC).74 8 [cm -3 ] (NV).7 9 [cm -3 ] ( e) -3 [cm ] ( p) -3 [cm ] 4.4(a)~(e)..5eV f T..5eV.7eV (ET) n (HT)
(a) ET=.eV (b) ET=.5eV ft ft.8.8.6.6.4.4..5 EV.5 Efn [ev].5.5.5.5 3 3.5 EC Efp [ev] 3 3.5 EC EV..5 EV.5 Efn [ev].5 3 3.5.5 EV EC.5.5 3 3.5 EC Efp [ev] ET=.7eV ET=.eV ft (c) ft (d).8.8.6.6.4.4. EV.5.5 Efn [ev].5 3 EC 3.5.5 3 EC.5.5 Efp [ev] 3.5 EV.. 5 EV.5 Efn [ev].5 3 3.5 EC.5 EV.5.5 3 3.5 EC Efp [ev] ET=.5eV.8 ft (e) 4.4 f T.6.4 (a)et=.ev (b)et=.5ev..5 EV.5 Efn [ev].5 3 3.5.5 EC EV 3.5.5.5 3 EC Efp [ev] (c)et=.7ev (e)et=.5ev (d)et=.ev p n-et-n n-ht-n p-et-p p-ht-p n-et-n n ( 4.5(a)) n-ht-n p pn ( 4.5(b)) p-et-p pn ( 4.5(c)) p-ht-p
(a) n (b) HT n ET n EC n EC EF EV EC (c) p ET p EF EV EC (d) p HT p EF EV EF EV 4.5 pn (a)n-et-n (b)n-ht-n (c)p-et-p (d)p-ht-p ( 4.5(d)) FET I-V SiO FET SiO FET SiO AlGaN ( 4.6(a)) ( 4.6(b)) N P
(a) (b) B =.8eV E C B =.8eV E C E F.6eV E F.6eV E V E V 4.6 (a) (b) N P n p FET FET ( 4.7) DEG V AlGaN DEG 4.8 N P SiO/AlGaN (ET) (HT) 4 N SiO/AlGaN ( 4.8(a)) n - -DEG n-n-n P ( 4.8(b)) p-n-n pn AlGaN DEG N ( 4.8(c)) n-p-n pn 3
Ec Ef AlGaN GaN AlGaN GaN Ev ET,HT (a) (b) AlGaN DEG n 4.7 FET (c) (d) 4.8 FET (a)n-e-n (b)p-e-n (c)n-h-n (d)p-h- AlGaN DEG P ( 4.8(d)) p-p-n DEG FET 4.9 N-ET-n P-ET-n DEG ( 4.9(b)) N-HT-n P-HT-n ( 4.9(c)) FET Id-Vg 4. N-HT-n P-HT-n FET P-ET-n VTV N-ET-n AlGaN pn 4
N,P E,H AlGaN Id DEG n P-E-n Vg s ( ) fn ( ) N-E-n N-H-n VT Vg Vg s fn 4. FET Id-Vg 4.9 (a) FET (b) N-E-n P-E-n (c) N-H-n P-H-n GR ( 4.3) ( 4.) SiO FET N-HT-n P-HT-n N-ET-n AlGaN FET AlGaN.3 SiO N-ET-n P-ET-n AlGaN AlGaN SiO N-HT-n P-HT-n 5
GaAs.8eV [] GaN.8eV FET HT pn AlGaN - - N-HT-N P-HT-P 4. N-HT-N P-HT-P V g N-HT-N g g g g g P-HT-P g g g 4. FET Id-Vg 4.3.V g V -V -4V -6V -8V g V 4. 4.3 SiO FET N-HT-N Ec Ef Ev (a) Ec Ef Ev (b) 4. FET (a)p-h-p (b)n-h-n 6
P-H-P Id I d [ A] 4 V d =.V V g =V V N-H-N Vg=Vg Vg 4. Id-Vg 4V 6V 8 6 4 V g [V] 4.3 Id-Vg FET AlGaN/GaN HEMT SiO SiO SiO FET SiO AlGaN 7
4 FET 5 ISE DESSIS 3 FET 3 DESSIS Si LSI GaAs 8
5. AlGaN/GaN HEMT AlGaN. 3nm GaN m AlGaN/GaN 3 cm - AlGaN GaN 4 cm -3 FET m 5 m.6 m 3.8 m SiO 6nm AlGaN/GaN Z Y X Gate SiO AlGaN GaN Source 5. 9
ev -3 cm SiO AlGaN 4 cm - SiO/AlGaN 5 3 cm -.V.5eV.5eV Vg -8V Id-Vg 5. FET -5.V gm.3 I d [ A] 5 E T =.5eV.eV Metal Gate..5eV 8 6 4 V g [V] 5. (Id-Vg ) 3
-5 S gm g µεε W = (5.) dl m V d ( : :AlGaN : d:algan W: L: Vd: ) gm (5.).5.eV..5eV 5 m 5.3 V.eV,.5eV V Energy [ev] 5 Gate 4 3 (a) 3 4 SiO /AlGaN Gate E C E F E V 5 3 4 5 X [ m] Energy [ev] 5 4 (b) 3 3 Gate 4 SiO /AlGaN E C E F E V Gate 5 3 4 5 X [ m] Energy [ev] 5 4 (c) Gate 3 3 4 SiO /AlGaN Gate E C E F E V 5 3 4 5 X [ m] 3 Energy [ev] 5 4 (d) 3 3 Gate 4 SiO /AlGaN 5 3 4 X [ m] 5.3 ( ) (a) ET=.eV, Vg=V (b) ET=.eV, Vg=-V (c) ET=.5eV, Vg=V (d) ET=.5eV, Vg=-V E C E F E V Gate 5
-V.eV V ev.5ev V.eV X=.6,4.4 m V X=.6,4.4 m.v 5.4 5.4 V.eV.5eV AlGaN/GaN cm- 3 (a) (b) (c) (d) 5.4 (Y=5. m) (a) E T=.eV Vg=V (b) ET=.eV g V =-6V (c) E T=.5eV g V =V (d) E T=.5eV g V =-6V 3
-6V.eV.5eV.eV -6V.5eV 4 cm - -3 cm 33
FET AlGaN/GaN HEMT SiO/AlGaN FET Id-Vg SiO FET AlGaN SiO FET SiO/AlGaN 4 FET 4 SiO/AlGaN OFF SiO 4 SiO 4 cm SiO 34
AlGaN/GaN HEMT RIE(Reactive Ion Etching) Ti/Al EB EB Ni/Au 35
3min 3min HPR83,5rpm(5sec)/3rpm(5sec)) (, 4min) 5sec MIF:H O=:3, 6sec 3 RIE BCl 3, SCCM; (8, 8min) 5W;.5minutes 4, ( ) 3min 3. 36
HPR83,5rpm(5sec)/3rpm(5sec)) (, 4min) 5sec MIF:H O=:3, 6sec (8, 8min) 5W, 4sec HCl:H O = :, min 3 EB Ti= 4 3min 3min 5 65, min, N 4. 37
HPR83,5rpm(5sec)/3rpm(5sec)) (, 4min) 5sec MIF:H O=:3, 6sec (8, 8min) 3 EB SiO,6 4 3.4 5. HPR83,5rpm(5sec)/5rpm(5sec)) (, 4min) 5sec MIF:H O=:3, 6sec (8, 8min) 5W, 4sec HCl:H O = :, min 3 EB Ni=5 Au=5 4 3.4 38
C-V C-V C-V ( ) AlGaN/GaN HEMT AlGaN AlGaN AlGaN n-gan AlGaN/GaN HEMT ( ) n-gan ε C = t GaN ε S depletion t = depletion ε GaNε V qn D bi kt q () ( ) AlGaN/GaN HEMT ε AlGaNε S C = () t AlGaN (C: : GaN:GaN AlGaN:AlGaN S: tdepletion: talgan:algan q: ND: Vbi: k: T: ) C-V Meter C G Y 39
n-gan S= m Vbi=.V ND= 7 cm -3 tdepletion=nm C=8pF C-V d V dy = qn D ε (3) (3) V () = dv dy y= W =, V ( W ) = V (4) (3) V qn D = ε y qn DW + ε y (5) W W = ε V qn D bi V kt q (6) ε C = = W V bi εqn D kt V q (7) C = εqn D V bi V kt q (8) /C -V 8 4
d C dv = εqn D (9) /C V (7) W= /C /C ND[cm -3 ] (/C )/dv Vg 3 /C -Vg Depth[nm] 4 4
3 TLM TLM(Transmission Line Model) GaN TLM TLM TLM (RS) (RC) (L) (W) (R) R L RC R = + () W W S L x R y y RC/W RS ( 3) RC 5 m m 5 m m 5 m 3 m TLM R RC RS RC =RC/W =Rs/W 3 L-R L 4
MOSFET 4 W[ cm] C[ cm ] RS[ ] V[V] 4 5 R dx I W S dv = (x) () W di = ρ C dx V ( x) (3) R dv = S I ( x) (4) dx W di W = dx ρ C V ( x) (5) (4) V [V] W [mm] c [ cm ] Rs [ ] 4 FET 43
+x V(x)+dV c /(Wdx) V(x) di I(x)-dI Rs dx/w I(x) 5 d V dx R = S I ( x) (4 ) W (4 ) (5) d V dx R = S V( x) (6) ρ C Rs/ c V γx γx ( x) = Ae + Be (7) - V(x) x= V=V A= B=V (7) V γx ( x) = Ve (8) I(x) (5) di dx W γx = Ve (9) ρc I x W V e γx ( ) = () ρcγ (8)() x= R V ( x) R = = I( x) ρc = W R ρ s c = V W V ρ γ c R ρ s W c ρ cγ = W () 44
W R = ρ [ mm] () C R S C () 45
4 (f T ) (e-capture) (e-emit) (p-capture) (p-emit) 4 4 ( ) e-capture dft dt = nc f ) () n ( T ( ) e-emit dft dt = e f () n T (i) (ii) ( ) p-capture dft dt = pc f (3) p T (iv) (iii) ( ) p-emit dft dt = e f ) (4) p ( T (f T : t: n: p: Cn: Cp: en: ep: ) Cn= nvthn Cp= pvthp n: p: vthn:vthp: 3kT/=mevthn /=mpvthp / 4 dft dt = nc f ) e f pc f + e ( f ) (5) n ( T n T p T p T :EF 46
+ = kt E E f F T T exp (6) (ET: ) T n T T n T f e N f C nn dt dn + = ) ( (7) (NT: ) dn/dt= en T T n n f f nc e = (8) (8) (6) + + = kt E E kt E E C kt E E N e F T F T n F C C n exp exp exp (9) n F T F C C n C kt E E kt E E N e = exp exp () n n T C C n C n C kt E E N e exp = = () = kt E E N n T C C exp () en ( T p T T p T f e N f C pn dt dp = ) (3) 47
f E E = = N exp C = p C (4) T T V e p pc p V p ft kt EV ET p = NV exp (5) kt (5) () (4) p dft dt n ( ft ) n Cn ft pc p ft + pc p ( ft ) = nc (6) (df T /dt=) f T f T ncn + pc p = (7) C n ( n + n ) + C p ( p + p ) 48
5 49
[] S. M. Sze, Physics of Semiconductor Devices nd Edition, pp.33, A Wiley-Interscience publication, 98 [] R. H. Dennard, F. H. Gaensslen, N. H. Yu, V. L. Rideout, E.Bassou, anda. R. LeBlanc, "Design of ion-implanted MOSFETs with very small physicaldimension," IEEE J.Solid-State Circuits, SC-9, pp.56 (974) [3],, GaN,, 69 7 () [4] M. A. Khan, J. N. Kuznia, A. R. Bhattarai, and D. T. Olson, "Metal semicoductor field effect transistor based on single crystal GaN," Appl. Phys. Lett., Vol. 6, No. 5, pp.786-788, April 993 [5] M. A. Khan, J. N. Kuznia, D. T. Olson, W. J. Schaff, J. W. Burm, and M. S. Shur, "Microwave performance of a.5 um gate AlGaN/GaN heterostructure field effect transistor," Appl. Phys. Lett., vol. 65, no. 9, pp.-3, 9 Aug. 994 [6] V. Kumar, W. Lu, R. Schwindt, A. Kuliev, G. Simin, J. Yang, M. Asif Khan, and Ilesanmi Adesida,"AlGaN/GaN HEMTs on SiC With f T of Over GHz," IEEE Electron Device Letters, Vol. 3, No. 8, pp.455-457, Aug. [7] Y. Ando, Y. Okamoto, H. Miyamoto, N. Hayama, T. Nakayama, K. Kasahara, M. Kuzuhara, "A -W AlGaN/GaN HETEROJUNCTION FET ON THINNED SAPPHIRE SUBSTRATE," IEEE International Elec tron Devices Meeting (IEDM) Technical Digest, pp.7.3.-7.3.4, () [8] M. Asif Khan, X. Hu, A. Tarakji, G. Simin, J. Yang, R. Gaska, and M. S.Shur, "AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors on SiC substrates," Appl. Phys. Lett. Vol. 77 No. 9, pp.339-34 () [9] S. Binari, K. Ikosssi, J. Roussos, W. Kruppa, D. Park, H. Dietrich, D.Koleske, A. Wickenden, and R. Henry, "Trapping Effects and Microwave Power Performance in AlGaN/GaN HEMTs," IEEE Trans. Electron Devices, Vol. 48 No. 3, pp.465-47 5
() [] K. Kunihiro, Y. Takahashi and Y. Ohno, "Improvement of Off-State Breakdown Voltage in Power GaAs MESFETs Based on Accurate Simulation Scheme," 998 IEEE International Electron Devices Meeting (IEDM) Technical Digest, pp.7-74 (998) [],, ( ), pp.43-44,, 989. [] Y. Ohno, P. Francis, M. Nogome and Y. Takahashi, "Surface-States Effects on GaAs FET Electrical Performance," IEEE Transactions on Electron Devices, 46, p.4-9 (999) [3],,,, " GaAs MESFET," ED 9-4 (99) 5
.,,, FET AlGaN/GaN HEMT,, ED- (). Katsushi Nishino, Daigo Kikuta, Shiro Sakai, Bulk GaN growth by direct synthesis method, Journal of Crystal Growth, 37-39, pp.9-95 (). Jin-Ping Ao, Daigo Kikuta, Yasuo Ohno, Copper-Gate AlGaN/GaN HEMTs with Low Gate Leakage Current,, ED- () 9 6 FET AlGaN/GaN HEMT FET AlGaN/GaN HEMT 5