Fabrication and Characterization of Schottky Diode for Efficient Semiconductor Devices
Explore the detailed process of fabricating and characterizing Schottky diodes, comparing their advantages and disadvantages over traditional pn junction diodes. Learn about Fermi level pinning, diffusion, thermionic emission, and more in semiconductor device technology.
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Presentation Transcript
: fermi level pinning barrier high
Diffusion for p-n diode (Shockley diode) Thermionic emission for Schottky diode
pn Pros The Schottky diode does not have the diffusion capacitance and hence its switching speed is much faster than pn diode. The turn on voltage of Schottky diode is less than pn junction. Cons The off current of Schottky diode is bigger than that of pn junction.
Io=A*T2???/?? A =A(2?? +4 ???? ?0 A=4????2 ) for Si ?0 3 A =4??? ?2 is the Richardson constant 3
bi=EF_metal-EF_semiconductor n Si p Si = . 1 = 12 E eV g ( ) q q E E bi Bp F V = 10 3 10 = n cm i 1 ( ) q q E E = ( ( )) q E E E bi Bn C F Bp g i F 2 1 = ( ( )) q E E E 1 N kT Bn g F i 2 = ( ln ) a q E Bp g 2 q n 1 N kT i = ( ln ) d q E Bn g 2 q n + 2 ( ) V i = bi W + dep 2 ( qN ) V qN = bi W a dep d = C A W = C A dep W dep + ( 2 ) 1 V = + bi ( 2 q ) 1 V = bi 2 2 C q N A 2 2 C N A a d
?????????,??? ?? ??? ????, ???
Generation & Recombination ?? 2?? ???= ???0[exp 1] Eg 2kT) ???0=???????????/(??+ ??) exp( pn ?? 2?? 1] Itotal= I + ???= I0exp qV/kT 1 +???0[exp
ideality factor n Ideal n=1 non ideal 1<n<2 Itotal ?3~20 5% n
101 Pt/n-Si 101 Current density ((A/cm2) Al/p-Si Current density ((A/cm2) n=1 @0.1V Ion/Ioff=105 100 10-1 n=1.6@ -0.1V Ion/Ioff=103 10-1 10-3 10-2 10-5 10-3 10-4 10-7 -2 -1 0 1 2 -2 -1 0 1 2 Voltage (V) Voltage(V) 2.0 8 Al/p-Si Pt/n-Si 1.6 6 y=1.02E23x+4.01E22 NA=1.2E15cm-3 bi=0.39eV Bp=0.64eV 1/C2 (x1023) 1.2 1/C2 (x1022) 4 0.8 y=-3.09E22x+1.77E22 ND=3.96E15cm-3 bi=0.57eV Bn=0.8eV 2 0.4 0.0 0 -1.0 -0.5 0.0 0.5 1.0 1.5 -1.5 -1.0 -0.5 0.0 0.5 1.0 Voltage(V) Voltage(V) 1. IV curve & CV curve 2. Find Schottky Diode ideality factor n Ion/Ioffratio 3. Find Nd(Na) bi Wd, B 4. Draw Band diagram 5. Comparison of Schottky and pn diode, pros and cons 6. Application of Schottky Diode
