Temperature dependence of optical anisotropy of birefringent porous silicon

Temperature dependence of the in-plane optical anisotropy of birefringent porous Si produced from a (110) Si wafer is studied. The anisotropy of refractive indices in the [001] and [1 (1) over bar0] directions increased about 0.3% when the temperature rose from 30 to 100 degrees C. The effective medium approximation could reproduce the experimental result in the low temperature range, while discrepancy appeared at high temperatures. The discrepancy suggests that the structural anisotropy of porous Si starts to relax at relatively low temperatures. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3453449]