Role of Resistance in Infrared Detectors

[nichthefish]

Hi, I constructed a device that consists of two metal pads atop a semiconductor material. I'm still confused on the whole Ohms law thing. Infrared radiation strikes the metal, and we're testing it at different temperatures, but I don't know what happens from there. My questions are:

1. Is the voltage applied to one metal pad or both (to generate current?)
2. What is the role of resistance?
3. Not sure if this is too specific, but why is a wider range of resistance good?

I'm not sure if I made any sense, but I would appreciate any kind of help. Thanks!

 

[Drakkith]

Ohms law states the relationship between Current, Voltage, and Resistance in an electronic circuit. Specifically I=V/R, which means that the current is equal to the voltage divided by the resistance.

Most of what you are asking is covered in any basic electronics book. I suggest picking one up at any bookstore or from online.

 

[nichthefish]

Thanks, I understand the actual law, I just don't know its importance in infrared detectors. That's my main question, sorry if I wasn't clear.

 

[CWatters]

I'm not familiar with the design you are talking about but my thinking would be..

1) You apply a voltage between the pads and measure the current flowing. From that you calculate the resistance?
2) The resistance depends on the IR radaition?
3) If the amount the resistance varies is large the detector is more sensitive? eg smaller temperature changes can be detected?

 

[CWatters]

Here you go...
http://en.wikipedia.org/wiki/Infrared_detector

The response time and sensitivity of photonic detectors can be much higher, but usually these have to be cooled to cut thermal noise. The materials in these are semiconductors with narrow band gaps. Incident IR photons can cause electronic excitations. In photoconductive detectors, the resistivity of the detector element is monitored.

So I suspect my earlier reply is along the right lines.