The authors present density functional theoretical results of electronic and optical properties of wurtzite-type CdS and CdSe semiconductor nanowires and bulks. The results show that quantum confinement will increase the energy gap, decrease the dielectric function, change the sign of birefringence, and increase the absolute value of birefringence at low-frequency region, as the dimensions of CdS and CdSe are reduced from the bulk to a nanowire with diameter of several nanometers. The optical spectral peaks of CdSe nanowires show redshifts as compared with the corresponding ones of CdS nanowires.
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This work was supported by National Basic Research Program of China (No. 2004CB720605), National Natural Science Foundation of China under projects (No. 20373073), Science Foundation of the Fujian Province (No. E0210028), and Foundation of State Key Laboratory of Structural Chemistry (No. 060007).