In semiconductor we have formulae to measure the valence band and conduction band density of states they depend on the density of states at reference temperature, which is 300 K. But how can we calculate the density of states at 300 K i.e., reference temperature.
Density of state (DOS) is temperature dependent.DOS at conduction band (Nc) and at valance band (Nv) at any temperature other than 300 K can be calculated by multiplying the DOS at 300 K( i.e reference temperature) by the ratio of that temperature to 300K with power of 3/2 .Now this ref. DOS at 300K can be calculated from a basic formula.Nc=2*((2*pi*effective electron mass*K*T)/h^2)^(3/2) .similarly Nv=2*((2*pi*effective hole mass*K*T)/h^2)^(3/2) .here k is boltzmann constant and h is plank's constant. effective electron and hole mass will vary from material to material which is an intrinsic property.
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