Displacement damage dose analysis of the output characteristics of In0.5Ga0.5P and Cu(In,Ga)(S,Se)2 solar cells irradiated with alpha ray simulated helium ions

To investigate applicability of radiation-hard indium–gallium–phosphide (InGaP) and copper–indium–gallium–sulfide–selenide (CIGS) solar cells to dosimeter devices without any modification, we irradiated high-energy He+ ions, which were simulated α-ray particles, to an InGaP and a CIGS solar cell. We found that both types of solar cells have sufficient resistance to He+ ions. By using displacement damage dose (DDD) analysis, the obtained He+ ion-induced degradation trends were compared with those induced by high-energy electrons, and we found that the degradation trends due to He+-ions, electrons, and protons aligned on the same curve when we plotted the data as a function of a modified DDD conversion equation, which originally was applied to space solar cells. The obtained DDD formulas enable us to predict the device lifetime or correction of an output signal for degradation when such solar cells are employed as a dosimeter.

Exploring the Thickness-Dependence of the Properties of Layered Gallium Sulfide

Group III layered monochalcogenide gallium sulfide, GaS, is one of the latest additions to the two-dimensional (2D) materials family, and of particular interest for visible-UV optoelectronic applications due to its wide bandgap energy in the range 2.35–3.05 eV going from bulk to monolayer. Interestingly, when going to the few-layer regime, changes in the electronic structure occur, resulting in a change in the properties of the material. Therefore, a systematic study on the thickness dependence of the different properties of GaS is needed. Here, we analyze mechanically exfoliated GaS layers transferred to glass substrates. Specifically, we report the dependence of the Raman spectra, photoluminescence, optical transmittance, resistivity, and work function on the thickness of GaS. Those findings can be used as guidance in designing devices based on GaS.

Ultrafast Nonlinear Optical Response and Carrier Dynamics in Layered Gallium Sulfide (GaS) Single-Crystalline Thin Films

Gallium sulfide (GaS) is a layered metal monochalcogenide semiconductor that has recently garnered considerable attention in various fields. In this study, we investigated the nonlinear absorption characteristics of multilayer β-GaS thin films on sapphire substrate by using femtosecond open-aperture Z-scan method. The β-GaS films exhibit saturable absorption behavior at 532 nm while nonlinear absorption appears under 650 nm excitation. The nonlinear absorption coefficient of β-GaS was determined to be −1.8 × 10–8 m/W and 4.9 × 10–8 m/W at 532 and 650 nm, respectively. The carrier dynamics of β-GaS films was studied via femtosecond transient absorption (TA) measurements. The TA results demonstrated that β-GaS films have broad photo-induced absorption in the visible regime and sub-nanosecond lifetime. Our results indicate that gallium sulfide has large nonlinear optical response and long carrier lifetime, which could be applied in future photonic devices.

A Discrete Ligand-Free T3 Supertetrahedral Cluster of Gallium Sulfide

Large discrete supertetrahedral clusters of metal chalcogenides are rare due to the difficulty of crystallizing solids in which the negative charge of the cluster is balanced by the positive charges of the countercations. Here, we describe a discrete ligand-free T3 supertetrahedral cluster, [Ga10S16(SH)4]6−, which was successfully synthesized in the presence of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) using the neutral surfactant polyethyleneglycol (PEG)-400 as the reaction solvent. Protonated DBUH+ cations are incorporated into the crystal structure of the product, which can be formulated as [C9H17N2]6[Ga10S16(SH)4]. This compound, which represents the first example of a discrete ligand-free T3 cluster of gallium sulfide, was fully characterized by single-crystal and powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis, and ultraviolet-visible diffuse reflectance. The results presented here indicate that the use of surfactants as solvents offers potential for the preparation of new compounds containing supertetrahedral clusters.

A high-performance visible-light-driven all-optical switch enabled by ultra-thin gallium sulfide

A 2D Ga2S3 enabled all-optical switch is realized upon a silicon-based on-chip platform. With the unique optical properties of the 2D nanoflakes, the device exhibits excellent switching behaviors driven by visible light at a low power density.