Reduction of optical reflection from InP semiconductor wafers after   high-temperature annealing
  We observed and studied strong reduction of optical reflection from the surface of InP wafers after high-temperature annealing. The effect is observed over a wide range of the incident wavelengths, and in the transparency band of the material it is accompanied by increasing transmission. The spectral position of a minimum (almost zero) of the reflection coefficient can be tuned, by varying the temperature and the time of annealing, in the spectral range between 0.5 and 6 eV. The effect is explained by the formation of a uniform oxide layer, whose parameters (thicknesses and average index) are estimated by detailed modeling. 
Oleg G. Semyonov, Arsen V. Subashiev, Alexander Shabalov, Nadia   Lifshitz, Zhichao Chen, Takashi Hosoda, and Serge Luryi
cond-mat.mtrl-sci physics.optics