<< Chapter < Page Chapter >> Page >
  1. XIV. What does the above Table refer to ? Describe the meaning of the terms entered in the boxes ? Answer: The angle between the Primary Flat of the Si Wafer and the Secondary Flat of the Si Wafer is ‘α’. Type tells if Si-Wafer is N-Type or P-Type. Orientation gives the cleavage plane Orientation in Miller Indices.[1/6+1/6+1/6=1/2Point]

XV. What do the different terms refer to in the above Integral Equation? Answer: N(E)=density of states per unit volume per unit energy, P(E) →Fermi-Dirac Statistics or the probability of occupancy at energy E by Fermions. dE → elemental energy, m*→effective mass of electron in the conduction band.X 0 →Fermi Level in Metal with respect to the bottom edge of the Conduction Band i.e.X 0 =E F - E C .[1/10+1/10+1/10+1/10+1/10=1/2 Points]

XVI.

In the adjacent equation and in Question XV, X 0 is the same parameter. What is this parameter. Answer: X 0 =E F - E C .[1/2 Point]

XVII.

What are the different parameters and what are their units ? Answer: E g is Band-Gap in eV and λ is the wavelength of the photon emitted accompanying the radiative transition from Conduction Band to the Valence Band.[1/4+1/4=1/2]

XVIII. Define the parameters and give the units ?

Semiconductor E g n i ε r (DC) ? ρ i (300K) N C N V
Si 1.12 1×10 10 11.7 5×10 22 /cc 3.2×10 5 3.2×10 19 /cc 1.8×10 19 /cc
Ge 0.67 2×10 13 16.2 4.4×10 22 /cc 48 1×10 19 /cc 5×10 18 /cc
GaAs 1.424 2.1×10 6 12.9 4.42×10 22 /cc 3.3×10 8 4.7×10 17 /cc 7×10 18 /cc

Answers: E g (eV) , n i (#/cc), ε r (DC) rel.permittivity (Dimensionless ), #density of atoms in the crystal , ρ i (300K) Intrinsic Resistivity in Ω-cm, N C _ Effective Density of States at E C, N V _ Effective Density of States at E V [1/14+1/14+1/14+1/14+1/14+1/14+1/14=1/7]

XIX.

Define the terms and give the units. v = 10 7 cm/s. What is this velocity. Answers: v drift = electric drift velocity(m/s), μ(mobility) (cm 2 /(V-s)), q=electric charge(Coulombs), τ scattering (Mean Free Path or Relaxation Time)(sec),m* e =effective mass of electron(Kg)[1/28,1/28,1/28,1/28,1/28,1/28,1/28, 1/28,1/28,1/28,1/28,1/28,1/28,1/28,=1/2]

XX.

This rule is called Matthiessen’s Rule. Define the parameter and give the units of the parameter. Answers:μ effective ,→ effective mobility, μ imp ,→mobility due to impurity scattering, μ lattice ,→mobility due to lattice scattering, cm 2 /(V-s), [1/8+1/8+1/8+1/8=1/2]

XXI.

What are these power laws. Answers: lattice scattering inverse 3/2 power law , impurity scattering 3/2 power law [1/4+1/4=1/2 points]

XXII. σ = qμn Define the terms and give the units. Answers: σ →conductivity(Siemens/cm), q→electronic charge(Coulomb),μ→mobility(cm 2 /(V-s),n→conducting electron number density[1/16+1/16+1/16+1/16+1/16+1/16+1/16+1/16=1/2 Points]

XXIII. What special information is given by this Table.

Metal Au Cu Ni Pt
Effective Mass/Free Mass of electron 1.1 1.01 28 13

Answers: Ni and Pt are heavy Fermionic Metals [1/4+1/4=1/2]

XXIV. What is the basic difference about electron transport reflected by the Table below ?

Element E F τ(femtosec) L(Angstrom) W F v e 1 (×10 5 m/s)
Li 4.7 9 90 9.96
Na 3.1 31 250 2.3 8.08
K 2.1 44 293 2.2 6.55
Cu 7.0 27 328 12.15
Ag 5.5 41 441.6 10.77
Ge E V +E G /2 2217 2106 1.16
Si E V +E G /2 767.6 729 1.16
GaAs E V +E G /2 4890 4645.5 1.16

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Electrical and electronic materials science. OpenStax CNX. May 01, 2014 Download for free at http://cnx.org/content/col11615/1.14
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Electrical and electronic materials science' conversation and receive update notifications?

Ask