摘要
The fundamental reflectivity spectra of Hg_(0.8)Cd_(0.2)Te have been investigated.The feature of the spectra is the presence of E_(1) and E_(2) peaks within the fundamental absorption region.A three dimensional saddle point is used to fit the E_(1) and E_(1)+Δ_(1) critical point and some simulated calculation is done for E_(2) at X point.The measured and calculated reflectivities are compared and prominent features of the reflectivity spectra are identified with critical point transition at the and X points in the Brillouin zone.