Ultrathin GaAs solar cells with a high surface roughness GaP layer for light‐trapping application

Abstract

By reducing the thickness of the absorber layers, ultrathin GaAs solar cells can be fabricated in a more cost-effective manner using less source material and shorter deposition times. In this work, ultrathin GaAs solar cells are presented with a diffuse scattering layer based on wide bandgap GaP grown directly on the device layers of the cells with MOCVD. The roughness and surface morphology are quantified using atomic force microscopy and the resulting diffuse scattering capability is assessed using wavelength-dependent reflectance measurements. Ohmic rear contacts are made using contact points etched through the GaP layer, for which an etching procedure using I 2 :KI was developed and optimized. The performance of the GaP textured ultrathin GaAs cells are compared with equivalent planar cells using current densityvoltage measurements and external quantum efficiency measurements, where the GaP textured cells demonstrate an increase of 6.7% in the short-circuit current density (J SC ), which was found to be as high as 21.9 mAÁcm À2 as a result of increased photon absorption by light-trapping.

Design and Performance Enhancement of a GaAs-Based Homojunction Solar Cell Using Ga0.5In0.5P as a Back Surface Field (BSF): A Simulation Approach

“…This layer acts as a window layer [12]. Similarly, as a window layer in the device, the semiconductor materials GaInP [13], ZnSe [14], and AlInP [15] can be used. The back contact of a solar cell is also the site of charge recombination processes.…”

Current Enhancement of Ultrathin GaAs Solar Cells with Rear Light Scattering Structures Using Block Copolymers

“…For the practical use of ultrathin GaAs solar cells with a light‐scattering structure, it is important to fabricate light‐scattering textured structures on areas as large as the solar cells at a low cost. Many fabrication methods have been studied, such as photolithography or nanoimprinting, [ 11,12 ] which transfer mask patterns onto semiconductor or dielectric films, wet etching using a special etchant, [ 13 ] growing semiconductor materials with different lattice constants on a GaAs substrate, [ 14,15 ] and others. Since the size and morphology of the mask can be controlled, photolithography and nanoimprinting methods are suitable for fabricating textured surfaces that efficiently scatter visible light.…”

“…The results demonstrate that the short-circuit current density is enhanced by 1.39 mA cm À2 , which improves the energy conversion efficiency by 0.71 percentage points compared with a reference cell without a rear-textured structure. using a special etchant, [13] growing semiconductor materials with different lattice constants on a GaAs substrate, [14,15] and others. Since the size and morphology of the mask can be controlled, photolithography and nanoimprinting methods are suitable for fabricating textured surfaces that efficiently scatter visible light.…”

Refining Photothermal Deflection Spectroscopy: Incorporating Reflectance for Enhanced Accuracy in Light‐Absorption Measurements

“…Specifically, they are important for the design and optimization of many optoelectronic devices, including optical transmission systems, photodiodes, and solar cells. [1][2][3][4][5][6][7] Thus, understanding the light-absorption properties of semiconductors directly contributes to improving the performance of these technologies and devices and opens up new application areas. A deep understanding of light-absorption properties enables us to conduct better material selection, refine manufacturing, device design, and performance optimization.…”

“…The internal absorptance is independent of the reflectance and thus suitable for evaluating the absorption properties of the material of the sample. The light absorptance has so far been calculated using Equation ( 1) or (2). In such R & T absorption measurements, the spectral resolution (SR) and lower limit of quantification are determined by the sensitivity of the spectrometer and photodetector.…”