Near-infrared transparent conductive electrodes based on composite GaAs-metal deep sub-wavelength high contrast grating

Abstract This paper demonstrates the fabrication of near-infrared transparent electrodes customized for specific light polarization. We achieve this by employing semiconductor deep subwavelength monolithic high-contrast gratings (MHCG) integrating metal stripes. Through the combination of GaAs-based MHCG with TiAu or Au stripes within a deep sub-wavelength grating, polarization selective transmission exceeding 80% over a wide spectral range is achieved for structures designed to operate around a wavelength of 940 nm for either TE or TM excitation. At maximum 85% transmission is reached which relates to 122% transmission with respect to the transmission through plain GaAs-air interface. Additionally, these structures exhibit low sheet resistance (1.4 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mstyle scriptlevel="0"/> <mml:msup> <mml:mtext>sq</mml:mtext> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ). Hybrid metal-stripes/MHCG grating (MetalMHCG) enables record-breaking polarized light transmission and electrical conductivity simultaneously. Our work represents the first demonstration of MetalMHCG in the near-infrared range, thanks to an advanced nanofabrication process of this sub- λ hybrid semiconductor/metal grating, showing optical and electrical properties not seen in alternative transparent conductive electrode designs. The proposed approach has the potential to enhance electrical injection uniformity in optoelectronic devices such as LEDs, semiconductor lasers and photodetectors.