Band Gap of LEDs
By Mohammad Reza Farham
Chemistry 222 Thursday 08.02.2012
Lab Partner: Thanh Nguyen ANALYSIS ANSWERS
Factors Affecting the Band Gap of LEDs
1. Based on your observations in Experiments 1 and 2, prepare a single table listing an approximate band gap energy, Eg compared to composition of the LEDs, as well as the voltage across each LED. Recall that Eg = hc/λ.
Band Gap Eg
2. Which compound has the larger bond length, GaP or GaAs? - GaAs
3. Which compound has the greater bond strength, GaP or GaAs?
4. Which compound has the greater ΔGaP or GaAs?
5. Which compound has the greatest degree of ionic character, GaP or GaAs? (You may wish to use a bond-type triangle to discuss this point.)
6. Rank the following LEDs that you used in lab in terms of increasing lattice spacing. (Lattice spacing reflects the average bond length between the III-V type atoms in the solid.)