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.c om ng cu u du o ng th an co Technical Review – Materials :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt Crystal structure c om ng cu u - du o ng - co - an - Basics A crystal is a repeating array = lattice + unit cell Lattice: pattern of repetition; point with identical surroundings for periodic stacking Unit cell: what is repeated; the simplest choice for a representative structural unit Lattice constant: length of unit cell edges (a, b, c) and angles between crystallographic axes (α, β, γ) th ‰ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt cu u du o ng th an co ng c om Example :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt ‰ ng co cu u du o ‰ an ‰ th ‰ Simple square Simple rectangle ng ‰ c om Point lattices for 2-D crystal :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt cu u du o ng th an co ng c om crystal systems There are only seven unique unit cell shapes to fill 3D space :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt cu u du o ng th an co ng c om 14 Bravais lattices There are only 14 ways to arrange lattice points in 3-D space :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt Indices of crystals Point xyz or (x,y,z) along a,b and c axis e.g 100, 111, ½½½, (1,0,0) ‰ Direction family of directions [hkl] individual direction Use the smallest integer positions = [111], [111], [ ], [ ], [ ], [ cu u du o ng th an co ng c om ‰ ], [ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com ], [ ] https://fb.com/tailieudientucntt cu u du o ng th an co ng c om ‰ Plane {hkl} family of planes: integer representing inverse of axial intercept (hkl) individual plane: Miller indices expressed by the inverse of axial intercept (hklm) for hexagonal system: Miller-Bravais indices :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com https://fb.com/tailieudientucntt Cubic system c om Angle between [hkl] and [mnp] cos θ = (hm + kn + lp) √(h2+k2+l2) √(m2+n2+p2) ng cu u ‰ (hkl) ⊥ [hkl] dhkl = a / √(h2+k2+l2) du o ‰ th an co ng ‰ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 10 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 98 https://fb.com/tailieudientucntt Resistivity ‰ c om cu u ‰ du o ng th an co ‰ Drift current: transport of carriers under the influence of electric field Electron current density: Jn = In/A = - qvnN/V = -qnvn = qnμn E where In = electron current A = cross sectional area Hole current density: Jp = Ip/A = qpvn = qpμp E Total current density: J = Jn + Jp = (qnμn+qpμp)E = σ E ng ‰ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 99 https://fb.com/tailieudientucntt .c om ng du o cu u ‰ ng th ‰ co ‰ Conductivity σ = qnμn+qpμp Resistivity ρ = 1/(qnμn+qpμp) For n-type ρ = 1/qnμn For p-type ρ = 1/qpμp an ‰ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 100 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 101 https://fb.com/tailieudientucntt Hall effect c om Hall effect: establishment of electric field from Lorentz force qEy = qvxBz qEy = qvxBz : Hall field th an z co ng ‰ cu u Bz Hall voltage, VH= Eyw y ng Ex du o V w Ey x Ey = (Jp/qp)Bz = RHJpBz Hall coefficient RH= 1/qp (for hole) I RH= -1/qn (for electron) :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 102 https://fb.com/tailieudientucntt .c om p = 1/(qRH)= JpBz/qEy ng = (I/A)Bz/[q(VH/w)] = IBzw/qVHA cu u du o ng th an co By Hall measurement, carrier concentration can be obtained :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 103 https://fb.com/tailieudientucntt ‰ ng du o cu u ‰ ng th an ‰ Diffusion current: transport of carriers from a spatial variation of carrier concentration Total current density: Jn = qnμn E + qDn dn/dx Jp = qpμp E - qDp dp/dx Total conduction current density: J = J n + Jp Einstein relation: Dn = (kT/q)μn co ‰ c om Drift and diffusion :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 104 https://fb.com/tailieudientucntt .c om p-n Junction Electrostatic potential When electric field is applied, Force on electron= -qE = -grad(E), where E = electron potential energy E = (1/q)dEi/dx (1) E = - dV/dx (2) Electrostatic potential: V = -Ei/q from (1) and (2) cu u du o ng th an co ng ‰ :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 105 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 106 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 107 https://fb.com/tailieudientucntt cu u du o ng th an co ng c om ‰ Effects of bias - Built-in potential - Transition region :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 108 https://fb.com/tailieudientucntt cu u du o ng th an co ng c om ‰ I-V characteristics :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 109 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 110 https://fb.com/tailieudientucntt .c om ng co an th ng du o u cu :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 111 https://fb.com/tailieudientucntt .c om References cu u du o ng th an co ng R A Colclaser and S Diehl-Nagle, “Materials and devices” C Kittel, “Introduction to Solid State Physics” Sze, “Physic of semiconductor devices” B G Streetman, “Solid state electronic devices” J F Shackelford, “Introduction to materials science for engineers” :: EAM 5715 Electronic Devices for Human Interface Systems (EDHIS) CuuDuongThanCong.com 112 https://fb.com/tailieudientucntt ... different orientations th an co ‰ c om Planar defects: 2-D cu u du o ng ‰ From http://www.ca.sandia.gov /Materials& EngineeringSciences/FocusAreas/thinfilm.html :: EAM 5715 Electronic Devices for Human... wavelengths rather than a continuous distribution Photoelectric effect: radiation from a heated materials is emitted in discrete units of energy (quanta); a characteristic minimum energy is required