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"The growth and crystallization processes of the Cu2ZnSnS4 (CZTS) phase typically rely on high-temperature sulfurization, which involves a harmful chalcogen-containing atmosphere. Together with the use of high-toxicity solvents, these processes could hinder the widespread adoption of this technology in the mass production of CZTS semiconductors for solar cell application. Thus, we studied the formation of CZTS films from ethanol-based precursors without the sulfurization step, fully employing the non-toxic solvent and avoiding the environmentally harmful sulfur-containing atmosphere. The certain addition of 2-mercaptopropionic acid led to the formation of a clear and stable sulfur-containing precursor. The precursors were successfully deposited onto soda lime glass by employing spin coater. CZTS crystallinity in the identified XRD patterns was vanishingly small in the case of eliminating the sulfurization process. Moreover, the carbon concentration and grain size of the resulting films were controlled by changing the time period of drying treatment during film fabrication. A drying time of 120 minutes, which demonstrated a CZTS grain size of ± 1 µm with a direct optical energy gap around 1.4 eV, was confirmed as the ideal condition. These results may provide a useful route toward environment-friendly strategies for the production of a CZTS semiconductor that is compatible with the absorber application in thin-film solar cells."

"Interaksi RKKY (Ruderman-Kittel-Kasuya-Yosida) adalah interaksi exchange tidak langsung antara dua buah momen magnet terlokalisasi yang dimediasi oleh elektron pita konduksi. Interaksi exchange tidak langsung dalam struktur multilayer magnetik spin valve bisa dimediasikan oleh elektron konduksi milik lapisan pemisah non-magnetik. Interaksi RKKY umum ditemukan pada struktur multilayer yang lapisan pemisahnya bersifat konduktor listrik. Namun dalam eksperimen ditemukan lapisan pemisah LaAlO3 dalam struktur spin valve bisa memediasikan interaksi exchange berjarak jauh meskipun memiliki sifat sebagai insulator. Dalam penelitian ini, kami meneliti mekanisme interaksi RKKY di dalam LaAlO3. Dalam eksperimen lain, ditemukan bahwa transfer muatan bisa menginduksi munculnya sifat konduktor pada LaAlO3. Untuk mempelajari efek transfer muatan, pendekatan density functional theory (DFT) dilakukan di dalam penelitian ini untuk mendapatkan struktur pita elektronik LaAlO3 dengan doping muatan. LaAlO3 yang tidak terdoping memiliki celah pita sebesar 3 eV dengan puncak pita valensi dan lembah pita konduksi masing-masing berada di titik R dan Γ. Kami menunjukkan sifat konduktor muncul dari energi Fermi yang meningkat melalui doping muatan. Dengan tambahan doping muatan pada perhitungan DFT, kami menunjukkan bahwa LaAlO3 bisa memiliki sifat konduktor yang sesuai dengan eksperimen transfer muatan pada LaAlO3. Selanjutnya, LaAlO3 bersifat konduktor bisa memediasi interaksi RKKY dalam struktur spin valve. Penelitian ini bermanfaat untuk aplikasi LaAlO3 dan semikonduktor dalam heterostruktur magnetik.

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RKKY interaction is an indirect interaction between localized magnetic moments mediated by conduction electron. Indirect exchange interactions between two magnetic layers in spin valve structure can be mediated by the conduction electron of the nonmagnetic spacer. RKKY exchange interaction is mostly found in magnetic multilayer involving conductor as the non-magnetic spacer. However, recent experiment shows that LaAlO3 spacer can intermediate of long-range exchange interaction even though it is an insulator. Here we study the mechanism of RKKY interaction in LaAlO3. An experiment shows that charge transfer can induce a conducting characteristic of LaAlO3. To study the effect of charge transfer, we perform a density functional theory (DFT) approach to obtain the band structure of LaAlO3 with charge doping. Undoped LaAlO3 has an indirect band gap around 3 eV with peak valence at R symmetry point and lowest conduction point at Γ point. We show that the conducting characteristic arise from Fermi energy shifts via charge doping. By adding charge doping into DFT calculation, we show that LaAlO3 can have conductor characteristic, in agreement with charge transfer experiment on LaAlO3. Furthermore, the conducting LaAlO3 is able to mediate RKKY interaction in spin valve structure. Our study is useful for application of LaAlO3 and semiconductor by extension in magnetic heterostructures."