I<answer>n</answer> the semico<answer>n</answer>ductor i<answer>n</answer>dustry, i<answer>n</answer>frared light ca<answer>n</answer> be used to characterize materials such as thi<answer>n</answer> films a<answer>n</answer>d periodic tre<answer>n</answer>ch structures. By measuri<answer>n</answer>g the reflecta<answer>n</answer>ce of light from the surface of a semico<answer>n</answer>ductor wafer, the i<answer>n</answer>dex of refractio<answer>n</answer> (<answer>n</answer>) a<answer>n</answer>d the exti<answer>n</answer>ctio<answer>n</answer> Coefficie<answer>n</answer>t (k) ca<answer>n</answer> be determi<answer>n</answer>ed via the Forouhi-Bloomer dispersio<answer>n</answer> equatio<answer>n</answer>s. The reflecta<answer>n</answer>ce from the i<answer>n</answer>frared light ca<answer>n</answer> also be used to determi<answer>n</answer>e the critical dime<answer>n</answer>sio<answer>n</answer>, depth, a<answer>n</answer>d sidewall a<answer>n</answer>gle of high aspect ratio tre<answer>n</answer>ch structures.
What letter represents the index of refraction?
n