Question 20N.3.hl.TZ0.14
| Date | November 2020 | Marks available | [Maximum mark: 3] | Reference code | 20N.3.hl.TZ0.14 |
| Level | hl | Paper | 3 | Time zone | TZ0 |
| Command term | Describe, Explain | Question number | 14 | Adapted from | N/A |
Doping of silicon increases the conductivity in semiconductors.
Describe the doping in p-type and n-type semiconductors.
[2]
p-type:
«small amount of» Group 13 element produces holes ✔
n-type:
«small amount of» Group 15 element adds extra electrons ✔
Award [1 max] for correct element type for p AND n OR p-type: “produces holes” AND n-type: adds extra electrons”.
The description of doping in p- and n-type semiconductors was well expressed and the majority scored both marks.
Doping of silicon increases the conductivity in semiconductors.
Explain how doping improves the conductivity of silicon.
[1]
electrons and holes flow in opposite directions
OR
electrons can flow into holes
OR
gap between valence and conduction bands becomes smaller ✔
The better candidates were able to explain how doping improves the conductivity of silicon and typically stated that electrons can flow into holes. The weaker candidates had some idea of what was involved but often were not able to articulate precisely in a scientific manner the process and hence usually failed to score the mark.
