Enhanced Hole Generation in Mg-Doped AlGaN/GaN Superlattices Due to Piezoelectric Field

2000 ◽  
Vol 39 (Part 1, No. 4B) ◽  
pp. 2428-2430 ◽  
Author(s):  
Kazuhide Kumakura ◽  
Toshiki Makimoto ◽  
Naoki Kobayashi
2000 ◽  
Vol 622 ◽  
Author(s):  
Kazuhide Kumakura ◽  
Toshiki Makimoto ◽  
Naoki Kobayashi

ABSTRACTWe achieved high hole concentrations above 1019 cm−3 at room temperature in Mg-doped InxGa1-xN/GaN (4 nm/4 nm) superlattices grown by metalorganic vapor phase epitaxy. The hole concentrations for the InxGa1-xN/GaN superlattices increased with the In mole fraction, and the maximum hole concentration reached 2.8 Å 1019 cm−3 for the In0.22Ga0.78N/GaN superlattice. The hole concentrations for the superlattices strongly depend on the structural parameters of the superlattices. The band bending due to the strain-induced piezoelectric field and the valence band structures of the InGaN/GaN heterostructures affect the hole generation in the superlattices. The weak temperature dependence of the resistivities for the InGaN/GaN superlattices with higher In mole fractions indicates highly efficient hole generation in the superlattice.


1999 ◽  
Author(s):  
Kazuhide Kumakura ◽  
Toshiki Makimoto ◽  
Naoki Kobayashi

2000 ◽  
Vol 39 (Part 2, No. 3A/B) ◽  
pp. L195-L196 ◽  
Author(s):  
Kazuhide Kumakura ◽  
Toshiki Makimoto ◽  
Naoki Kobayashi

2017 ◽  
Author(s):  
K. Ebata ◽  
J. Nishinaka ◽  
Y. Taniyasu ◽  
K. Kumakura
Keyword(s):  

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Yifan Li ◽  
Ronghuan Wu ◽  
Li Yu ◽  
Miaoda Shen ◽  
Xiaoquan Ding ◽  
...  

AbstractBioactive ceramics are promising candidates as 3D porous substrates for bone repair in bone regenerative medicine. However, they are often inefficient in clinical applications due to mismatching mechanical properties and compromised biological performances. Herein, the additional Sr dopant is hypothesized to readily adjust the mechanical and biodegradable properties of the dilute Mg-doped wollastonite bioceramic scaffolds with different pore geometries (cylindrical-, cubic-, gyroid-) by ceramic stereolithography. The results indicate that the compressive strength of Mg/Sr co-doped bioceramic scaffolds could be tuned simultaneously by the Sr dopant and pore geometry. The cylindrical-pore scaffolds exhibit strength decay with increasing Sr content, whereas the gyroid-pore scaffolds show increasing strength and Young’s modulus as the Sr concentration is increased from 0 to 5%. The ion release could also be adjusted by pore geometry in Tris buffer, and the high Sr content may trigger a faster scaffold bio-dissolution. These results demonstrate that the mechanical strengths of the bioceramic scaffolds can be controlled from the point at which their porous structures are designed. Moreover, scaffold bio-dissolution can be tuned by pore geometry and doping foreign ions. It is reasonable to consider the nonstoichiometric bioceramic scaffolds are promising for bone regeneration, especially when dealing with pathological bone defects.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Muhammad Ikram ◽  
Sidra Aslam ◽  
Ali Haider ◽  
Sadia Naz ◽  
Anwar Ul-Hamid ◽  
...  

AbstractVarious concentrations of Mg-doped ZnO nanorods (NRs) were prepared using co-precipitation technique. The objective of this study was to improve the photocatalytic properties of ZnO. The effect of Mg doping on the structure, phase constitution, functional groups presence, optical properties, elemental composition, surface morphology and microstructure of ZnO was evaluated with XRD, FTIR, UV–Vis spectrophotometer, EDS, and HR-TEM, respectively. Optical absorption spectra obtained from the prepared samples showed evidence of blueshift upon doping. XRD results revealed hexagonal wurtzite phase of nanocomposite with a gradual decrease in crystallite size with Mg addition. PL spectroscopy showed trapping efficiency and migration of charge carriers with electron–hole recombination behavior, while HR-TEM estimated interlayer d-spacing. The presence of chemical bonding, vibration modes and functional groups at the interface of ZnO was revealed by FTIR and Raman spectra. In this study, photocatalytic, sonocatalytic and sonophotocatalytic performance of prepared NRs was systematically investigated by degrading a mixture of methylene blue and ciprofloxacin (MBCF). Experimental results suggested that improved degradation performance was shown by Mg-doped ZnO NRs. We believe that the product synthesized in this study will prove to be a beneficial and promising photocatalyst for wastewater treatment. Conclusively, Mg-doped ZnO exhibited substantial (p < 0.05) efficacy against gram-negative (G-ve) as compared to gram-positive (G+ve) bacteria. In silico molecular docking studies of Mg-doped ZnO NRs against DHFR (binding score: − 7.518 kcal/mol), DHPS (binding score: − 6.973 kcal/mol) and FabH (− 6.548 kcal/mol) of E. coli predicted inhibition of given enzymes as possible mechanism behind their bactericidal activity.


2021 ◽  
Vol 141 ◽  
pp. 110817
Author(s):  
Nasrin Sabet Sarvestani ◽  
Mohammad Tabasizadeh ◽  
Mohammad Hossein Abbaspour Fard ◽  
Hamed Nayebzadeh ◽  
Thuy Chu Van ◽  
...  

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