Passivation of InP solar cells using large area hexagonal-BN layers

Abstract

Surface passivation is crucial for many high-performance solid-state devices, especially solar cells. It has been proposed that 2D hexagonal boron nitride (hBN) films can provide near-ideal passivation due to their wide bandgap, lack of dangling bonds, high dielectric constant, and easy transferability to a range of substrates without disturbing their bulk properties. However, so far, the passivation of hBN has been studied for small areas, mainly because of its small sizes. Here, we report the passivation characteristics of wafer-scale, few monolayers thick, hBN grown by metalorganic chemical vapor deposition. Using a recently reported ITO/i-InP/p+-InP solar cell structure, we show a significant improvement in solar cell performance utilizing a few monolayers of hBN as the passivation layer. Interface defect density (at the hBN/i-InP) calculated using C–V measurement was 2 × 1012 eV−1cm−2 and was found comparable to several previously reported passivation layers. Thus, hBN may, in the future, be a possible candidate to achieve high-quality passivation. hBN-based passivation layers can mainly be useful in cases where the growth of lattice-matched passivation layers is complicated, as in the case of thin-film vapor–liquid–solid and close-spaced vapor transport-based III–V semiconductor growth techniques.

Towards Integration of Two-Dimensional Hexagonal Boron Nitride (2D h-BN) in Energy Conversion and Storage Devices

“…Recently, 2D h-BN has been introduced as a promising passivation layer for InP as a highperformance III-V semiconductor. Raj et al [170] exploited five and seven-layer thickness of 2D h-BN to passivate InP solar cells in order to reduce the recombination phenomenon caused by the surface defect states (Figure 12a-c). The calculated number for the interface defect density was 2 × 10 12 eV −1 cm −2 , which is better than the results of other passivation layers such as Al 2 O 3 , HfO 2 , and SiO 2 with interface defect density of 2.6 × 10 12 eV −1 cm −2 , 5.4 × 10 12 eV −1 cm −2 , and 5 × 10 12 eV −1 cm −2 , respectively [171,172].…”

Topical review: pathways toward cost-effective single-junction III–V solar cells

“…Moreover, at present, 2D materials are attracting a lot of interest for their exciting optoelectronic applications. We showed that hBN could indeed provide very good passivation as well as selectivity for InP [282]. However, the mechanism of charge carrier selectivity and passivation using 2D materials is very different compared to that of 3D materials such as ZnO, TiO 2, or Ta 2 O 5 .…”

“…We postulated that the electron selectivity of hBN is due to the accumulation of electrons at the hBN/i-InP interface, which reduces the barrier height for electron tunnelling and increases the barrier height for holes tunnelling. Passivation, on the other hand, was achieved through a combined effect of quantum mechanical tunnelling and interface charge transfer [282].…”

Advances in boron nitride‐based materials for electrochemical energy storage and conversion

“…In the past decade, efforts have been made to design and modify the interfaces to facilitate electronic transport with lower possible probability of charge carrier recombination in solar cells 211 . 2D h‐BN appears as an attractive material to design passivate or interface layers of heterojunctions in solar cells, such as Si‐based, 90,212 perovskite, 213 and organic 214 solar cells. Besides, h‐BN adopted as antireflection 216 and back‐sheet layer 217 in solar cells have also been investigated.…”