# Varshni Empirical Expression

1. Oct 28, 2009

### Bloodthunder

Not exactly a homework question, but I wasn't sure if this should go to the general forums or homework forums since this is regarding schoolwork.

I was doing an experiment regarding the conductivity of semiconductors and temperature (from rtp to 500 K) and I feel that in my calculations, I measured the $$E_{g}(0)$$. However, the professor was saying that I measured instead the value $$E_{g}$$, which is constant for low temperatures.

My reason for thinking that I got $$E_{g}$$ was I was reading up on semiconductors and came across this expression $$E_{g}(T) = E_{g}(0) - \frac{\alpha*T^2}{\beta+T}$$, $$E_{g}$$ refer to the energy gap of the semiconductor, $$\alpha$$ and $$\beta$$ are constants associated with the semiconductor and T is the temperature. I was just wondering if this worked over the entire range of temperature or only over a specific range?