EGA108 / EG-279 ASSESSED SHEET 1
To be handed in via Blackboard by 5pm on Thurs Nov 8th. Show your workings in all cases – if you want to include hand-written workings, embed these as a scanned or photographed image. e = 1.6 x 10-19 C NA = 6.03 x 1023 me = 9.11 x 10-31 kg kB = 1.38 x 10-23 JK-1
By: darky- 712402
1 List two aspects of materials behaviour that the Drude model can explain.

The Drude model can explain the Thermal Conductivity in metals and Electrical Conductivity of metals.

List two aspects of materials behaviour that the Drude model can’t explain but the Quantum Free Electron model can.

Explains the effects of the temperature, impurities, and deformation on Electrical Conductivity in which the Drude Model
In the semiconductors holes and electrons are generated in pairs and the number of electrons/hole pairs is dependent on the temperature. So when temperature increases the mobility of the electrons and holes decrease, and the number of holes and electrons increase exponentially. Therefore their will be more for the current to flow through meaning it will have higher conductivity.
Silicon is a semiconductor and its electron configuration is 1s2 2s2 2p6 3s2 3p2 , so in the outer most electron configuration silicon have 2 electrons filling the p band. And because it is a semiconductor it will have the properties, therefore as temperature increases the conductivity will too.
[2 marks for each part]

4 Of the following materials, which would be suitable to produce a visible light LED. Explain your answer.
GaN Direct band gap of 3.4 eV GaP Indirect band gap of 2.32 eV
InGaN Direct band gap of 2.2 eV GaAs Direct band gap of 1.5 eV
Si Indirect band gap of 1.17 eV InAs Direct band gap of 0.43 eV

First to create an LED the Semi-Conductor should have a direct band gap, so the recombination of holes and electrons will involve no change of momentum thus the by-product of this recombination which is the energy can be released as photons. Therefore the GaN, InGaN, GaAs, and InAs can all be considered candidates for visible light LED; however the GaAs produces infrared light which is not a visible light and the InAs is used to create infrared