Materials Science and Engineering - Electronic and Mechanical Properties of Materials Part 8 pdf

... Tuller-2001 For R 9 3.225 9 Equation of Motion - Impact of Collisions Assume: • probability of collision in time dt = dt/τ • time varying field F(t) v(t+dt) = ( 1- dt/τ) {v(t) +dv} = ( 1- dt/τ) ... L/Wt = ρ L/A ⇒ρ(οhm-cm) σ = 1/ρ ⇒ σ (οhm-cm) -1 ⇒σ (Siemens/cm) (Test your dimensions: σ=E/j=neµ) Ohms/square ⇒ Note, if L=W, then R= ρ /t independent of magnitude...

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... Eg=1.1eV, and let µ e and µ h be approximately equal at 1000cm 2 /V-sec (very good Si!). σ~10 10 cm -3 *1.602x10 -1 9 *1000cm 2 /V-sec=1.6x10 -6 S/m, or a resistivity ρ of about 10 6 ohm-m max. ... conduction band or valence band by using a modified expression for the energy of an electron in the H atom 2222 4 6.13 8 nnh me E o n −== ε 2 * 22222 4* 222...

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... conductivity: σ = 4.4×10 -1 8 S cm -1 8 9 10 11 12 13 10 -7 10 -6 10 -5 10 -4 Y-cut σ 0 = 2.1 S cm -1 E A = 105 kJ mol -1 10 4 /T [1/K] σ [S cm -1 ] 900 80 0 700 600 500 T [°C] ... Photo Electro-chemical Etching - PEC • Electro-chemical etching p-type + - Light source • Photo electro- chemical etching + - h + h + semiconductor...

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... T = 80 0 °C log(pO 2 / bar) 0.995 1,005 -1 6 -4 0 -5 -4 -3 -2 -1 0 1 donor acceptor -2 0 -1 2 -8 donor doped acceptor doped 2 3.225 15 Designer Wavelengths Variation of band-gap ... composition x of In 1-x Ga x As. © H.L. Tuller, 2001 3.225 16 Band-Gap Colors Mixed crystals of yellow cadmium sulfide CdS and black cadmium selenide CdSe....

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... (xrays) can be ‘particle-like’ • DeBroglie – matter can act like it has a ‘wave-nature’ • Schrodinger, Born – Unification of wave-particle duality, Schrodinger Equation Wave-particle Duality: ... E. Fitzgerald-1999 3.225 18 Ψ must be able to represent everything from a particle to a wave (the two extremes) Unification: Wave-particle Duality wave particle ( tkxi Ae ω− =Ψ k and p...

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... when you join these together? © E. Fitzgerald-1999 3.225 12 - - + + + + Holes diffuse Electrons diffuse + + + + - - - - + + + + - - + + + + An electric field forms due to ... 3.225 11 The p-n Junction (The Diode) • Note that dopants move the fermi energy from mid-gap towards either the valence band edge (p-type) or the conduction band edge (n-t...

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... ε s © E. Fitzgerald-1999 ) ) ] 3.225 18 Orientational Polarizability • No restoring force: analogous to conductivity H H O p + - C O O p=0 +q -q θ For a group of many molecules ... − = 1 © E. Fitzgerald-1999 9 3.225 11 Interaction of the d orbitals of a central ion with six ligands in an octahedral arrangement. Octahedral Environment of Transition Met...

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... are:) n=1,2,3,… =0,1,2,…,n-1 m l =- , - +1,…,0,…, , (m s =+ or - 1/2) l l l l 0 -1 3.6eV U(r) © E. Fitzgerald-1999 ) in -1 3.225 9 Diffraction Picture of the Origin of Band Gaps Probability Density=probability/volume ... / 1.35/ ? 5.66 / 5.65 / ? 5 08 / 7 98 / ? 0. 08 /0. 18 / 1.45 6.45 / 6.09 / ? IV / III-V / II-VI* ∗ Fill in as many of the question marks as...

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... material Material Type χ Paramagnetic +10 -5 -1 0 -4 Diamagnetic -1 0 -8 -1 0 -5 Ferromagnetic +10 5 2 5 3.225 5 © E. Fitzgerald-1999 Microscopic Source of Magnetization • No monopoles • magnetic ... 2(atomic distance cinteratomi 2 >≡ a r r J is a function of distance! 8 3.225 8 © E. Fitzgerald-1999 Ferromagnetism M T T C () ( ) () ( ) 1. 4-1 .3...

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... e -i(kx-ωt) are all waves e -i(kx-ωt) is the complex one and is the most general real imaginary A Acosθ iAsinθ θ e iθ =cosθ+isinθ © E.A. Fitzgerald-1999 1 3.225 11 Wiedmann-Franz ... out of phase with E ω<<1/τ, p in phase with E ω i eE p 0 0 = 0, →∞→ pω τ 00 eEp = © E.A. Fitzgerald-1999 3.225 2 Complex Representation of Waves sin(kx-ωt), cos(kx-ωt...

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