Properties of liquid phase deposited aluminium oxide thin film on black silicon fabricated by aluminium-assisted chemical etching

Abstract This work studies the antireflection properties of liquid phase deposited aluminium oxide (LPD-Al 2 O 3 ) thin film on black silicon (b-Si) fabricated by aluminium-assisted chemical etching (AACE). The morphological and optical characteristics of the LPD-Al 2 O 3 are subsequently illustrated. The weighted average reflection ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">R</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">avg</mml:mi> </mml:mrow> </mml:msub> </mml:math> %) of mono c-Si is reduced from 44.9% to 33.7% (within 300–1100 nm wavelength region) after the deposition of the LPD-Al 2 O 3 . Alternatively, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">R</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">avg</mml:mi> </mml:mrow> </mml:msub> <mml:mspace width="1em"/> </mml:math> of b-Si is reduced from 9.4% to 7.6% when deposited with LPD-Al 2 O 3 . Based on the absorption result, potential <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">J</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">sc</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>max</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:msub> </mml:math> for the planar c-Si is shown to increase from 22.5 mA cm −2 to 26.3 mA cm −2 after the deposition of LPD-Al 2 O 3. Besides, the calculated potential <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">J</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">sc</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>max</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:msub> </mml:math> for the b-Si increased from 35.5 mA cm −2 to 36.2 mA cm −2 after the deposition of the LPD-Al 2 O 3 .