Wafer-Scale Synthesis and Optical Characterization of InP Nanowire Arrays for Solar Cells.

Lukas Hrachowina,Magnus T Borgström,Nicklas Anttu

doi:10.1021/acs.nanolett.1c02542

Lukas Hrachowina, Magnus T Borgström + Show 1 more

Open Access

https://doi.org/10.1021/acs.nanolett.1c02542

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Abstract

Nanowire solar cells have the potential to reach the same efficiencies as the world-record III–V solar cells while using a fraction of the material. For solar energy harvesting, large-area nanowire solar cells have to be processed. In this work, we demonstrate the synthesis of epitaxial InP nanowire arrays on a 2 inch wafer. We define five array areas with different nanowire diameters on the same wafer. We use a photoluminescence mapper to characterize the sample optically and compare it to a homogeneously exposed reference wafer. Both steady-state and time-resolved photoluminescence maps are used to study the material’s quality. From a mapping of reflectance spectra, we simultaneously extract the diameter and length of the nanowires over the full wafer. The extracted knowledge of large-scale nanowire synthesis will be crucial for the upscaling of nanowire-based solar cells, and the demonstrated wafer-scale characterization methods will be central for quality control during manufacturing.

Highlights

Wafer-scale patterning necessary for NW synthesis has been shown by the use of nanoimprint lithography (NIL)[27] and displacement Talbot lithography (DTL).[28]
We have studied the homogeneity of the material’s quality across the wafer by measuring PL and time-resolved photoluminescence (TRPL) maps
Cross-sectional scanning electron microscopy (SEM) showed an excellent agreement with the dimensions obtained by these optical measurements

Summary

■ INTRODUCTION

Nanowires (NWs) are promising candidates for future solar cells.[1−3] They hold the potential to reach the high efficiencies of world-record III−V semiconductor technology while using only about 10% of the material.[4,5] NWs have unique advantages, such as the possibility to be integrated in polymers[6−9] to create flexible solar cells with high efficiencies. By the creation of a simulated database that describes the reflectivity of NWs with a given diameter (D) and length (L), it is possible to extract those parameters from ex situ reflectivity measurements. This method has been used to measure the homogeneity across a small NW-array sample by time-consuming manual movement of the measurement spot over a 2 mm long line across the sample.[30] Here, we use a PL mapper equipped with a white light source to automatically measure several thousand reflectivity spectra and utilize such a Received: June 29, 2021 Revised: August 19, 2021 Published: August 27, 2021. Letter database extraction method to extract maps of the NW diameter and length over the full 2 inch wafer

■ RESULTS AND DISCUSSION

■ CONCLUSION

■ REFERENCES