Holographic Grating Formation by Wet Etching of Amorphous As_<40>Ge_<10>Se_<15>S_<35> Thin Film

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Amorphous As_<40>Ge_<10>Se_<15>S_<35> thin films have been studied with the aim of identifying optimum etching conditions that can be used to produce holographic grating structures for use as diffractive optical elements. We have fabricated holographic gratings using 632.8 am HeNe laser light. In addition, the fabricated gratings are developed with a method involving wet etching a using NaOH etching solution with one of three concentrations (0.26 N, 0.33 N, 0.40 N). The formed grating profiles were observed by atomic force microscopy which showed that the expected grating profile could be achieved by controlling the etching time. The maximum diffraction efficiency of a grating formed by two-beam interference without the etching process is 0.88%. The diffraction efficiency increases with time by selective etching. When the formed grating is etched using 0.26 N NaOH, the highest diffraction efficiency for these gratings was attained and the value was about 5.05%. NaOH solutions used in these experiments are suitable for the fabrication of relief gratings in As_<40>Ge_<10>Se_<15>S_<35> layers with A = 1.82 μm. Better results will be obtained by optimizing the etching conditions (concentration, etching time, temp. etc.).
社団法人応用物理学会の論文
2002-06-30