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The reverse bias stability is a key concern for the commercialization and reliability of halide perovskite photovoltaics. Here, the robustness of perovskite‐silicon tandem solar cells to reverse bias electrical degradation down to −40 V is investigated. The two‐terminal tandem configuration, with the perovskite coupled to silicon, can improve the solar cell resistance to severe negative voltages when the tandem device is properly designed. While perovskite cells typically exhibit early reverse bias breakdown voltages, the serial connection with silicon cells with large shunt resistances and high voltage breakdown limits their negative polarization and prevent the passage of large current densities when reverse biased. The importance of careful optical design is illustrated, with bottom‐limited conditions required to prevent the perovskite top cell from exploring its own breakdown. This aspect is of great importance in the case of partial shading events when the solar spectrum is richer in the IR components than the standard AM1.5G. Notably, 100% of efficiency retained after polarization at −40 V in different stressing conditions is observed. The results presented suggest that standard industrial bypass diode schemes may be compatible with silicon/perovskite tandem photovoltaics and provide new guidelines for the standardization of the stressing protocols. [ABSTRACT FROM AUTHOR]

Herein, the interest of a sputtering power reduction during physical vapor deposition (PVD) of the rear side indium‐based transparent conduction oxide (TCO) is investigated to reduce the In consumption in silicon heterojunction (SHJ) solar cells. Halving the supplied power allows for a TCO thickness reduction of 50%. Process fine‐tuning is shown to retain satisfying TCO electrical properties, thus preventing unwanted additional resistance losses despite the drastic reduction in TCO thickness. The produced SHJ solar cells with a 50% reduced TCO thickness show similar performances to those made with the reference process. Using thinner TCO layers at the cell backside is, however, found to come with a bifaciality penalty, which is discussed in detail. [ABSTRACT FROM AUTHOR]

We compared the radiation tolerance of nanocrystal and floating gate memories, fabricated with the same technology. We investigated the effects of 5-MeV proton and 10-keV X-Ray irradiations, focusing on the charge loss, the permanent degradation of the electrical characteristics, and the data retention. We also presented a first order model of the charge loss and the permanent threshold voltage shift. The model and the experimental results show that nanocrystal memories feature improved radiation robustness against total ionizing dose. Nanocrystal memories can withstand a radiation dose 3 and 10 times larger than floating gate memories, in terms of charge loss and data retention, respectively. Index Terms--CMOS memory integrated circuits, flash memories, radiation effects, semiconductor devices reliability, semiconductor memories.

We present the first charge loss model of heavy ion induced radiation damage on nanocrystal memory cells. The model takes into account the nanocrystal distribution non uniformity and the effect of different programming techniques, which may produce non uniform charging of the nanocrystals. The model has been validated with a focused microbeam test. It provides an estimation of both the ion track size and the average number of ion hits required for achieving a given charge loss. In our irradiation experiments we estimated an ion track size (diameter) of 85 nm for 50-MeV Cu ions. This model confirms also the good robustness of nanocrystal memories against heavy ion irradiation and their much stronger tolerance than the conventional floating gate based memories. Index Terms--CMOS memory integrated circuits, flash memories, heavy ion irradiation, radiation effects, semiconductor device reliability, semiconductor memories.

We present new results on heavy-ion irradiation of nanocrystal non-volatile addressable memory arrays. We show that the effects of a single ion hit are negligible on these devices due to the discrete nature of the storage sites. We estimate that, in order to observe an appreciable threshold voltage shift, at least three to four ion hits are needed. Despite several cells experiencing multiple hits they are still functional after the irradiation, showing no changes on the retention characteristics. These results highlight an outstanding improvement of the nanocrystal technology over the conventional floating gate memories in terms of radiation tolerance, which are encouraging for a potential application in radiation harsh environments. Index Terms--CMOS memory integrated circuits, heavy ion irradiation, radiation effects, semiconductor device reliability, semiconductor memories.

The full process integration of nano-crystal (NC) memory cells in a stand-alone 16-Mb NOR Flash device is examined. The findings suggest that NC sizes, dispersion and the interpoly dielectric structure are responsible for affecting the electrical performances related to reliability issues.

Proton irradiation of nanocrystals memories produces peculiar radiation effects on the electrical characteristics of these devices, owing to their thin tunnel oxide and to the presence of nanocrystals replacing the conventional flash memory floating gate. In this work, we show that the data retention capability is compromised only after high fluences and that irradiated devices do not show accelerated degradation during subsequent electrical stresses. The presence of nanocrystals instead of a floating gate reduces also the quantity of charge lost during irradiation, indicating these devices as possible candidates for space and avionic environments. Index Terms--CMOS memory integrated circuits, nonvolatile memories, proton irradiation, radiation effects.

In this work we focused our attention on heavy ion irradiation effects on nanocrystal memory cell arrays. All cells are fabricated by depositing Si nanocrystai on top of a Si[O.sub.2] layer. Immediately after irradiation we observed neither charge loss following the ion hit, nor appreciable change of the electrical characteristics of the nanocrystai MOSFETs, such as transconductance and drain current decrease. In addition, despite the gate oxide leakage current may show a large increase after irradiation with high energy ions, the data retention time of the cells is not compromised, due to the discrete nature of the nanocrystal storage node. Index Terms--CMOS memory integrated circuits, heavy ion irradiation, non-volatile memories, radiation effects.

Direct solar hydrogen generation via a combination of photovoltaics (PV) and water electrolysis can potentially ensure a sustainable energy supply while minimizing greenhouse emissions. The PECSYS project aims at demonstrating a solar‐driven electrochemical hydrogen generation system with an area >10 m2 with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers (ECs) using thin‐film silicon, undoped, and silver‐doped Cu(In,Ga)Se2 and silicon heterojunction PV combined with alkaline electrolysis to form one unit are developed on a prototype level with solar collection areas in the range from 64 to 2600 cm2 with the solar‐to‐hydrogen (StH) efficiency ranging from ≈4 to 13%. Electrical direct coupling of PV modules to a proton exchange membrane EC to test the effects of bifaciality (730 cm2 solar collection area) and to study the long‐term operation under outdoor conditions (10 m2 collection area) is also investigated. In both cases, StH efficiencies exceeding 10% can be maintained over the test periods used. All the StH efficiencies reported are based on measured gas outflow using mass flow meters. [ABSTRACT FROM AUTHOR]

The improvement of tandem hydrogenated amorphous/microcrystalline Si solar cells under prolonged exposure to reverse bias direct current electric fields and illumination has been investigated. In this work, the authors show that the application of reverse bias stress in the presence of illumination slows down the solar cell ageing kinetics (caused mainly by the Staebler-Wronski effect and by the increase in the series resistance) and, in suitable conditions, it produces an improvement of the solar cell characteristic parameters as a function of stress time. The authors discuss the effect of temperature, electric field intensity, and illumination level. [ABSTRACT FROM AUTHOR]