Small bandgap IR detectors need to work in crogenic temperature

  • Thread starter chenhon5
  • Start date
  • #1
18
0

Main Question or Discussion Point

Is any body can give me a detailed explanation or reference why the small bandgap IR detectors (eg. InSb photodetecotr) need to work in the cryogenic temperature?

In addition, any body knows what is carrier capture time? Since some article said the photodetector detectivity is proportional to the square root of the carrier capture time, so increased capture time have the potential for higher temperature operation. Any thought? Thanks.
 

Answers and Replies

  • #2
mgb_phys
Science Advisor
Homework Helper
7,774
12
A small band gap means that very little energy is needed to knock an electron out of the band and make it conduct.
At room temperature there is enough thermal energy to do this with a large number of electrons.
It depends on how much sensitivity you need, how strong your signal is compared to the thermal noise, so firefighters infrared displays aren't cooled but astronomical cameras are.
 
  • #3
18
0
A small band gap means that very little energy is needed to knock an electron out of the band and make it conduct.
At room temperature there is enough thermal energy to do this with a large number of electrons.
It depends on how much sensitivity you need, how strong your signal is compared to the thermal noise, so firefighters infrared displays aren't cooled but astronomical cameras are.
Thank you for your reply. As I know the energy due to the temperature is k*T=0.0259eV, however, the bandgap of InSb is about 0.17eV, which is much larger than the thermal noise. Do you mean even the bandgap of InSb is larger than the thermal noise, but their values are more closed than other materials (say 1eV), so they will knock out much more electrons than wide bandgap materials?

Do you have an idea for the second question for my post about the carrier capture time?
 

Related Threads for: Small bandgap IR detectors need to work in crogenic temperature

  • Last Post
Replies
4
Views
8K
  • Last Post
Replies
7
Views
4K
  • Last Post
Replies
11
Views
5K
  • Last Post
Replies
1
Views
581
Replies
6
Views
802
  • Last Post
Replies
4
Views
1K
Replies
22
Views
5K
Replies
4
Views
23K
Top