We report the development of high-performance AlGaN/AlN heterostructure-field-effect-transistor-type (HFET) photosensors with a p-type GaN optical gate and detection wavelengths that are restricted to 220–280 nm. These photosensors employ a two-dimensional electron gas induced at the hetero-interface between Al0.6Ga0.4N and Al0.5Ga0.5N as a highly conductive channel. In addition, a p-type GaN optical gate is employed to deplete a channel. Consequently, we obtained a high photosensitivity of over 4 × 103 A/W and an externally low dark current density of approximately 5 × 10−10 A/mm at a source–drain voltage of 3 V. We also determined that the detection range of light wavelength in these HFET photosensors can be controlled by controlling the AlN molar fraction in the AlGaN channel layer. The results are very promising for the development of completely solar-blind high-performance photosensors with high photosensitivity.
High-performance AlGaN/AlGaN hetero-field-effect-transistor (HFET)-type photosensors with high photosensitivity were fabricated using p-type GaN comprising three-dimensional island crystals. The p-type GaN layers were grown on AlGaN layers at a high AlN molar fraction, and the area of p-type GaN comprising three-dimensional island crystals increased as the thickness of the p-type GaN film decreased, resulting in a reduced p-type GaN coverage ratio. The p-type GaN layers comprising three-dimensional island crystals and showing low coverage ratios were then used to fabricate HFET-type photosensors with high photosensitivity. A high light sensitivity of 1.5 × 104 A/W was obtained at a source–drain voltage (V SD) of 0.5 V for a photosensor with a p-type GaN thickness of 20 nm. Moreover, the dark current was suppressed to 10−10 A/mm and the photosensor achieved an extremely high photocurrent to dark current density ratio.
Background: Cisplatin, a platinum complex discovered by Rosenberg in 1969, has long been known as the first metal-based anticancer agent. Since then, various similar derivatives of cisplatin have been investigated for pharmacological activity, and the approved complexes have been applied as drugs. Objectives: The aims of the current study are: 1) to summarize the advantages and dose-limiting effects of the approved and unapproved chemotherapy platinum cytostatics, 2) to develop new strategies for the development of platinum anticancer drugs, and 3) to clarify the important factors for the mechanism of action of platinum complexes. Methods: A search was conducted in the literature databases, and the obtained information was summarized and analyzed. Results: Myelosuppression is the main dose-limiting effect and the reason for the disapproval of platinum complexes, such as picoplatin, enloplatin, miboplatin, sebriplatin, zeniplatin, spiroplatin, iproplatin, and ormaplatin. From the basic point of view of inorganic coordination chemistry, such as theoretical calculations, crystal structures of model complexes, docking structures with nucleic acid molecules, spectroscopy, and biological aspects, the importance of physicochemical properties of inorganic platinum complexes for their mechanism of action has been indicated. Spectroscopic methods, such as FTIR, NMR, X-ray crystal structure analysis, and fluorescence microscopy, are important for the investigation of the conformational changes in the binding of platinum complexes and DNA. Conclusion: In the development of platinum complexes, strong anti-cancer drug activity, low toxicity, and resistance can be obtained by the application of polynuclear platinum agents, complexes with targeted activity, and nanoparticle formulations. Electronic structure, stereochemical, and thermodynamic properties are essential for understanding the reaction mechanism of platinum complexes.
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