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The expansion of photovoltaic systems emphasizes the crucial requirement for effective operations and maintenance, drawing insights from advanced maintenance approaches evident in the wind industry. This review systematically explores the existing literature on the management of photovoltaic operation and maintenance. Through the integration of bibliometric analysis and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, 186 articles are selected for further comprehensive review. The selected articles are examined and categorized into four interconnected research domains: maintenance strategies, performance indicators, degradation modeling, and maintenance optimization and planning. The presented analysis underscores the importance of integrating maintenance strategies to enhance system effectiveness. It also emphasizes the necessity of a systematic approach that integrates reliability assessment with economic and technical considerations to optimize maintenance planning and enhance system availability and resource efficiency. This aligns with the Sustainable Development Goals for affordable, reliable, and sustainable energy, while also ensuring grid security. Furthermore, the study identifies gaps and proposes avenues for improvement, recommending a shift towards prognostic approaches and the advancement of predictive maintenance in photovoltaic systems. Key suggestions also include customizing metrics for large installations, implementing adaptive protocols that move away from traditional component-centric scheduling, and using reinforcement learning to prioritize risk and optimize long-term performance. Compared to previous reviews focusing on specific maintenance elements, this work provides a broader perspective by incorporating planning and organizational factors into the maintenance discussion. [Display omitted] • A comprehensive analysis of research publications on PV O&M management. • PRISMA framework and bibliometric analysis are applied. • PV maintenance is less developed than other operational aspects in the field. • Significance of proactive maintenance and data-driven decision-making is emphasized. • Gaps and future research directions for PV O&M management are proposed. [ABSTRACT FROM AUTHOR]

In this paper, a low temperature deposition of germanium (Ge) films on silicon (Si) is performed using Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RF-PECVD). A two-step temperature technique and different GeH 4 flow rates have been employed during the deposition process. The structural and the optical properties of 700 nm Ge films have been investigated using high resolution scanning electron microscopy, atomic force microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and variable angle spectroscopic ellipsometry. Study of the surface morphology of low temperature Ge seed layer revealed that a surface roughness as low as 0.5 nm can be achieved with in-situ low temperature annealing in rich H 2 chamber. Also, the fast Fourier transform pattern taken at the same area imaged by TEM for the seed layer exhibited crystalline nature due to the hydrogen induced crystallization. In addition, the RF-PECVD method promotes the nanocrystals growth at low temperature via plasma contribution. The XRD data shows that polycrystalline Ge layers with four different orientation and average crystallizes size of 43 nm on Si substrate is achieved. Furthermore, the post annealing treatment of the films at T < 600 °C enhances its electrical and transport characteristics. The optical characteristics of the Ge-on-Si shows high absorption coefficient (approximately one order of magnitude higher than bulk Ge at 1.5 μm) in the near-infrared (1.5–1.6 μm). [ABSTRACT FROM AUTHOR]

In this paper, electrophoretic method (EPD) is used to deposit 40 nm gold nano-particles (GNPs) on atomic layer deposited (ALD) grown oxides. Ultra-High Resolution Scanning Electron Microscopy (HRSEM) has been used to study the distribution of gold nano-particles on both Al 2 O 3 and HfO 2 thin films as a function of dipping time. The results show better distribution and mechanical adhesion of GNPs on top of HfO 2 compared to Al 2 O 3 . Additionally, metal-oxide-semiconductor (MOS) structures with GNPs embedded within the HfO 2 layers are fabricated. The distribution and coverage of the GNPs are analyzed using hysteresis loop of capacitance-voltage measurements at (1.0 MHz) and by quantifying the threshold voltage shift (ΔVt). Moreover, the distribution of the GNPs as function of dipping time is discussed in terms of the measured ΔVt. The results show an increase in ΔVt with longer dipping time followed by a drop in the ΔVt. Moreover, the Vt shift vs. dipping time indicates changes in the electrophoretic mobility behavior and the final distribution of GNPs on the surface of the HfO 2 . [ABSTRACT FROM AUTHOR]

We show a reduction in the interface trap density (Dit) at the amorphous-silicon/crystalline-silicon interface by annealing in nitrogen (95%) and hydrogen (5%) for 10, 20 and 25min at 400°C. Fabricated a-Si(n+)/c-Si(p)/c-Si(p+) heterojunction solar cells were measured both in the dark and optically under 1 sun after annealing. The dark current reduces from ∼9.5×10−4 mA/cm2 at −0.5V to ∼3.02×10−5 mA/cm2 after annealing for 25min at 400°C. Under AM1.5G the open circuit voltage (V oc) increases from 0.57V to 0.62V. The short circuit current density (J sc) increases from 12.1mA/cm2 to 13.2mA/cm2 and the fill-factor (FF) increases from 61.18% to 68.07%. The efficiency increases from 4.28% to 5.55%. The peak External Quantum Efficiency (EQE) increases from 55% to 63%. In addition, the Dit profile at the a-Si/c-Si interface is modeled and simulated. Trap Assisted Tunneling (TAT) model along with electric field enhancement via the Poole Frenkel Effect is included as Electron–Hole–Pair (EHP) generation mechanisms. Combining the simulation and annealing results reveals a 90% reduction in Dit at the a-Si/c-Si interface. [ABSTRACT FROM AUTHOR]

Among the limiting factors that affect the performance of Graphene (Gr)/ Silicon (Si) Schottky barrier solar cells (SBSC) - are the high recombination at Gr/Si interface and the growth of undesirable native oxide that resulted in instability issue. In this work, hafnium oxide (HfO 2 ) grown by atomic layer deposition (ALD) has been investigated as an interfacial layer for Gr/Si Schottky junction solar cells. Engineering the interface with HfO 2 contributed to enhancing the power conversion efficiency remarkably from 3.9% to 9.1%. The obtained efficiency with HfO 2 interfacial layers grown by ALD is considered among the highest reported for Gr/Si SBSC using pristine graphene. [ABSTRACT FROM AUTHOR]

The performance of thin-film amorphous silicon-based n + -i-p + solar cells in the presence of an exterior top thin film of mono-dispersed ultra-small 2.85 nm diameter silicon nanoparticles has been examined. The silicon nanoparticles have a 530–700 nm red luminescence band with a band peak at 628 nm. Reflectance and the external/internal quantum efficiency (EQE/IQE) of the devices were measured over the range of 300–800 nm. With the Si NPs there is a reduction in reflectivity, which improves the coupling of light to the solar cell. The enhancement in IQE is found to be over the spectral slice 360–610 nm lying between the confinement and the direct band gaps. An enhancement in the IQE in the range of 390–530 nm with a maximum of 31% at 445 nm and a smaller one in the range of 530–610 nm with a maximum of 11% at 590 nm was observed. The increase in the spectral response corresponds to 11.42% increase in short circuit current in agreement with our J – V measurements. The IQE enhancement is explained in terms of two competing channels: excitonic radiative recombination down-conversion in the range 530–610 nm and charge separation and collection in the range 360–530 nm. [ABSTRACT FROM AUTHOR]

In this paper, we systematically investigate the use of multilayer antireflection coatings (ARC) on GaAs 0.69 P 0.31 /Si dual-junction solar cells for achieving broadband reflection suppression. We incorporate dispersion, absorption, and both coherent and incoherent interference, by modeling the solar cell as a multilayer medium of thin films and a substrate, using the transfer matrix method. The analytical model is verified through reflectance measurements on a GaAs (1 −x ) P x /GaP stack. Our results show that optimized double- and triple-layer ARCs can minimize reflectance to below 5% within the spectral range of ∼400–945 nm, with the latter maintaining this performance over a broader spectrum of 390–1000 nm, in comparison to 25–45% reflectance for the bare solar cell. [ABSTRACT FROM AUTHOR]

In this paper, the effect of gold nanoparticles on n-i-p a-Si:H solar cells with different intrinsic layer (i-layer) thicknesses has been studied. 100 nm and 500 nm i-layer based n-i-p a-Si:H solar cells were fabricated and colloidal gold (Au) nanoparticles dispersed in water-based solution were spin-coated on the top surface of the solar cells. The Au nanoparticles are of spherical shape and have 100 nm diameter. Electrical and quantum efficiency measurements were carried out and the results show an increase in short-circuit current density ( J sc ), efficiency and external quantum efficiency (EQE) with the incorporation of the nanoparticles on both cells. J sc increases from 5.91 mA/cm 2 to 6.5 mA/cm 2 (∼10% relative increase) and efficiency increases from 3.38% to 3.97% (∼17.5% relative increase) for the 100 nm i-layer solar cell after plasmonic enhancement whereas J sc increases from 9.34 mA/cm 2 to 10.1 mA/cm 2 (∼7.5% relative increase) and efficiency increases from 4.27% to 4.99% (∼16.9% relative increase) for the 500 nm i-layer cell. The results show that plasmonic enhancement is more effective in 100 nm than 500 nm i-layer thickness for a-Si:H solar cells. Moreover, the results are discussed in terms of light absorption and electron hole pair generation. [ABSTRACT FROM AUTHOR]

Highlights: [•] a-Si p–i–n solar cells with plasmonic gold nanoparticles were fabricated. [•] Seven sizes i.e. 10, 20, 50, 80, 100, 200 and 400nm gold nanoparticles were used. [•] Improved spectral response; the median reflectivity drops from ∼23% to ∼18%. [•] Jsc increases from 9.34 to 10.1mA/cm2 with the plasmonic nanoparticles. [•] The efficiency is increased from 4.28% to 5.01%. [Copyright &y& Elsevier]

Highlights: [•] Fabricated 2μm-thick Si1−xGe x based solar cells with x =0, 0.25, 0.41 and 0.56. [•] Novel strained-Si layer grown on Si1−xGe x improves the solar cell performance. [•] J sc increases from ∼14mA/cm2 for Si cells to 21mA/cm2 for the Si0.44Ge0.56. [•] Improved spectral response for Si1−xGe x solar cells compared to Si demonstrated. [Copyright &y& Elsevier]

Abstract: Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO x N y ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin (∼2nm) strained-Ge channel heterostructure MOSFETs exhibited >4× mobility enhancements over bulk Si devices and >10× BTBT reduction over surface channel strained SiGe devices. [Copyright &y& Elsevier]