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The exceptionally low reflectance of black silicon (Si) across a broad wavelength range makes it an intriguing surface texture for solar cell applications. Si heterojunction (SHJ) solar cells fabricated on black Si formed by dry reactive ion etching using inductive coupled plasma on n-type Si are explored. The study is focused on the properties of the a-Si:H/ crystalline silicon interface, being a key issue for the photovoltaic performance of SHJ. Deep-level transient spectroscopy detected no radiation defect in Si after the etching. The surface of black Si was passivated with an intrinsic a-Si:H layer, followed by the deposition of p-type and n-type a-Si:H on the front and back sides, respectively. The SHJ solar cell photovoltaic performance based on black Si is strongly influenced by defect density at the a-Si:H/Si interface. Admittance spectroscopy and effective charge carrier lifetime measurements demonstrate that interface defect density decreases with the increase of (i) a-Si:H thickness. The value of 0.75 ms effective charge carrier lifetime was reached for single (i) a-Si:H layer passivation and 0.25 ms when (p)a-Si:H was deposited over the intrinsic a-Si:H layer. The measured open circuit voltage values for the SHJ solar cells increase with the (i) a-Si:H layer thickness reaching 658 mV. However, the fill factor decreases with increasing (i) a-Si:H layer thickness, limiting the efficiency at the maximum value below 14% due to the thickness uniformity of the a-Si:H layer. The development of conformal growth of a-Si:H is a key issue for further improvement of black Si heterojunction solar cell photovoltaic performance. [ABSTRACT FROM AUTHOR]

The possibility of using admittance spectroscopy to characterize the quality of ITO/MoOx/n-Si structures is shown. It has been demonstrated that magnetron evaporation of ITO layer at room temperature leads to the formation of radiation defects in the near-surface region of Si near the MoOx/Si interface with a depth of 0.13 and 0.26 eV below the conduction band with a capture cross-section of (1–5) × 10–19 and (5–10) × 10–19 cm–2, respectively. An increase in the deposition temperature of the ITO layer to 130°C allows reducing the concentration below the sensitivity leading to a significant improvement of solar cells characteristics. [ABSTRACT FROM AUTHOR]

The possibility of creating a lower junction for the multijunction A3B5/Si-type solar cells based on the n-GaP/p-Si heterostructure grown by the combined method of plasma enhanced atomic-layer deposition and metalorganic vapor-phase epitaxy is demonstrated for the first time at temperature Ts not exceeding 650°C. The photoelectric properties of the structures grown at Ts ≤ 650°C depend on the process conditions—in particular, on the use of additional treatment in Ar plasma. [ABSTRACT FROM AUTHOR]

The capability of plasma‐enhanced atomic layer deposition (PE‐ALD) for the formation of GaP nucleation layers on Si substrates for further epitaxial growth is explored. The possibility of epitaxial growth of GaP by metalorganic vapor phase epitaxy (MOVPE) on templates prepared by PE‐ALD GaP/Si is demonstrated. The structural and electronic properties of the interfaces between the GaP nucleation layer and the Si substrate as well as their thermal stability are studied. Initially, the GaP/Si structures obtained by PE‐ALD without additional hydrogen plasma exhibit better photoelectric properties compared with that fabricated with high H2 plasma power that induces the formation of defects in the silicon subsurface layer. Annealing at temperatures of 550–600 °C leads to a decrease in the defect concentration created by the hydrogen plasma. Thus, after annealing, the GaP/Si interfaces fabricated by both types of PE‐ALD processes exhibit similar quality. Thermal treatment of the GaP/Si structures at temperatures of 725–750 °C leads to the diffusion of phosphorus from GaP into Si and to the formation of an isotype n‐GaP/n–p‐Si heterojunction with improved photoelectric properties. High‐temperature stability of the GaP/Si interface fabricated by PE‐ALD is essential for its prospective use for GaP/Si templates. [ABSTRACT FROM AUTHOR]

Low-temperature plasma enhanced atomic layer deposition (PE-ALD) was successfully used to grow silicon (Si) doped amorphous and microcrystalline gallium phosphide (GaP) layers onto p-type Si wafers for the fabrication of n-GaP/p-Si heterojunction solar cells. PE-ALD was realized at 380 °C with continuous H2 plasma discharge and the alternate use of phosphine and trimethylgallium as sources of P and Ga atoms, respectively. The layers were doped with silicon thanks to silane (SiH4) diluted in H2 that was introduced as a separated step. High SiH4 dilution in H2 (0.1%) allows us to deposit stoichiometric GaP layers. Hall measurements performed on the GaP:Si/p-Si structures reveal the presence of an n-type layer with a sheet electron density of 6–10 × 1013 cm−2 and an electron mobility of 13–25 cm2 V−1 s−1 at 300 K. This is associated with the formation of a strong inversion layer in the p-Si substrate due to strong band bending at the GaP/Si interface. GaP:Si/p-Si heterostructures exhibit a clear photovoltaic effect, with the performance being currently limited by the poor quality of the p-Si wafers and reflection losses at the GaP surface. This opens interesting perspectives for Si doped GaP deposited by PE-ALD for the fabrication of p-Si based heterojunction solar cells. [ABSTRACT FROM AUTHOR]

Significant progress in photovoltaic conversion of solar energy can be achieved by new technological approaches that will improve the efficiency of solar cells and make them appropriate for mass production. A new technological approach for the growth of III-V compounds on Si substrates using low temperature plasma-enhanced atomic layer deposition (PE-ALD) is explored in the paper. This technique, which consists of alternatively changing the phosphorus and gallium atom source flows providing the growth of one monolayer by cycle, was developed for the growth of GaP films on Si substrates in a standard PECVD setup at 380 °C using PH3 and TMG (Trimethylgallium) as sources of III and V atoms. First (n)GaP/(p)c-Si anisotype heterojunction solar cell structures fabricated by PE-ALD exhibit open circuit voltage values similar to that obtained for (n)a-Si:H/(p)c-Si heterojunctions fabricated using the same (p)c-Si substrates. However (n)GaP/(p)c-Si solar cells demonstrates a potential to extend a high quantum efficiency in the short wavelength region due to lower absorption losses in the GaP emitter layer. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cooling of solar cells installed on the surface of moving vehicle was simulated. [•] Energy balance of solar cell was taken into account as boundary condition for CFD. [•] Results were experimentally verified for a flat module. [•] Simplified solution of energy equation for fixed velocity field was recommended. [•] Overheating was obtained for photovoltaic modules in flow separation regions. [Copyright &y& Elsevier]

The properties of n‐GaP/p‐Si interface as well as their influence on solar cell performance are studied for GaP layers grown by low‐temperature (380 °C) plasma‐enhanced atomic layer deposition (PE‐ALD). The influence of different plasma treatments and RF power values are explored. The increase of RF power leads to a growth transition from amorphous (a‐GaP) to microcrystalline GaP (μc‐GaP) with either amorphous‐GaP/Si or epitaxial‐GaP/Si interface, respectively. However, when continuous hydrogen plasma is used the amorphous‐GaP/Si interface exhibits better photovoltaic performance compared to the epitaxial one. Values of open circuit voltage, Voc = 0.45–0.55 V and internal quantum efficiencies, IQE > 0.9 are obtained for amorphous‐GaP/Si interfaces compared to Voc = 0.25–0.35 V and IQE < 0.45 for epitaxial‐GaP/Si interfaces. According to admittance spectroscopy and TEM studies the near‐surface (30–50 nm) area of the Si substrate is damaged during growth with high RF power of hydrogen plasma. A hole trap at the level of EV + (0.33 ± 0.02) eV is detected by admittance spectroscopy in this damaged Si area. The damage of Si is not observed by TEM when the deposition of the structures with epitaxial‐GaP/Si interface is realized by a modified process without hydrogen plasma indicating that the damage of the near‐surface area of Si is related to hydrogen plasma interaction. [ABSTRACT FROM AUTHOR]