Efficient three-dimensional nanostructured photoelectric device by Al-ZnO coating on lithography-free patterned Si nanopillars

Abstract

An efficient three-dimensional (3D) nanostructure photoelectric device is presented. An Al-doped ZnO (AZO) coating was applied to lithography-free patterned Si nanopillars and spontaneously formed a radial heterojunction (n-AZO/p-Si) photodiode having a quality ideality factor of 1.64. A significantly enhanced photocurrent of 5.45 mA/cm2 was obtained from the 3D nanostructure relative to that of a planar substrate (1.1 mA/cm2). This enhancement is induced by enlargement of the light-active surface area and an anti-reflection effect. Due to the intermediate refractive index of AZO, the reflection was distinctively reduced in the air-Si system. It discusses an effective approach for realizing nanostructured photoelectric device.

Metal/Semiconductor and Transparent Conductor/Semiconductor Heterojunctions in High Efficient Photoelectric Devices: Progress and Features

“…The studies of Si nanowire (SiNW) [14][15][16] or Si nanopillar (SiNP) [17][18][19] for solar cell applications are having the feasibility to enlarge the lightactive surface region. The efficient light harvesting system by implementing SiNP has been demonstrated experimentally by Jee et al [20]. SiNPs were created by lithography-free approach, thereby reducing the manufacturing cost.…”

“…This is achieved by implementing SiNPs which were fabricated through lithography-free patterning, with AZO film in photoelectric devices. The enlargement of the 3D light-active surface has strong potential to enhance the performance of conventional Si-based photoelectric devices with cost effective design including films, nanowires, nanotubes, nanoparticles, and nanodomes [6,12,20,[63][64][65][66]. The ITO nanodome structures added further optical benefit via significant reduction in the reflection.…”

“…The reflectance profiles from planar Si, AZO-coated planar Si, SiNPs, and AZO-coated SiNPs. A comparative significant reduction of reflection was observed in AZO-coated SiNPs and nanopillar textured substrate[20].…”

“…Cross-sectional SEM image of n-AZO/p-SiNP sample showing high density Si nanopillars with top AZO transparent electrode[20]. The reflectance profiles from planar Si, AZO-coated planar Si, SiNPs, and AZO-coated SiNPs.…”

Tunable antireflection from conformal Al-doped ZnO films on nanofaceted Si templates

“…An optimal antireflective surface should contain subwavelength features where the index matching at the substrate interface leads to improved AR performance. For instance, by using a surface texture on TCO (e.g., AZO) [ 6 ] and/or Si substrate [ 7 ], one can govern the light propagation and in turn the AR property due to the formation of graded refractive index [ 8 , 9 ]. In particular, for solar cell applications, a patterned AZO film on a flat silicon substrate shows a significant decrease in average reflectance up to 5% [ 10 ], whereas a thick AZO layer on silicon nanopillars is found to give an overall reflectance of approximately 10% [ 7 ].…”