Question

Consider the following semiconductors CuBr, and GaAs. All of these compoun approximately the same bond length However, each of these materials has band gap energy (Eg) due to differences in bon polarity. 3.00 ZnSe CuBr Eg at 300 K (CV) . GaAs 0.50 G 0.00.00 0.20 0.40 0.60 0.80 A Electronegativity 1.00

Answer 1

Answer: Part (B) bandgap energy is inversely proportional to bond polarity.

Bond polarity increases mean bond becomes more polar or ionic bond so the energy gap difference decreases. For covalent bond energy difference increases.

Electronegativity difference between bonding atoms Bond type Zero Pure covalent Bond Type Electronegativity Difference Intermediate Polar covalent Covalent character decreases; ionic character increases. pure covalent < 0.4 polar covalent between 0.4 and 1.8 Large Tonic ionic > 1.8

Electrons in a polar covalent bond are shifted toward the more electronegative atom; thus, the more electronegative atom is the one with the partial negative charge. The greater the difference in electronegativity, the more polarized the electron distribution and the larger the partial charges of the atoms.

Part (C) GaAs

Photon Energy: - (Planck Equation) E = hv = Where, E = Photon Energy -34 h = Planck constant =6.6261 x 10 J*S C = Speed of light = 3 x 108 m/s 2 = Photon wavelength V = Photon frequency

Take wavelengt inbetween 0.81 to 0.89 micrmeter = 0.85 micrometer.

E = (6.626*10^-34 * 3*10⁸ ) / (0.85*10^-6) = 2.3*10^-19 J = (2.3*10^-19)/(1.6*10^-19) = 1.46 eV.

So, from comparing this energy in the plot it will be GaAs.