In this work,a non-toxic and environmentally friendly aqueous-solution-based method has been adopted to prepare gadolinium-doped hafnium oxide(HfO2) gate dielectric thin films.By adjusting the gadolinium(Gd) doping co...In this work,a non-toxic and environmentally friendly aqueous-solution-based method has been adopted to prepare gadolinium-doped hafnium oxide(HfO2) gate dielectric thin films.By adjusting the gadolinium(Gd) doping concentration,the oxygen vacancy content,band offset,interface trap density,and dielectric constant of HfGdOx(HGO) thin films have been optimized.Results have confirmed that HGO thin films with Gd doping ratio of 15 at.% have demonstrated appropriate dielectric constant of 27.1 and lower leakage current density of 5.8×10-9 A cm-2.Amorphous indium-gallium-zinc oxide(α-IGZO) thin film transistors(TFTs) based on HGO thin film(Gd:15 at.%) as gate dielectric layer have exhibited excellent electrical performance,such as larger saturated carrier mobility(μsat) of 20.1 cm2 V-1 S-1,high on/off current ratio(Ion/Ioff) of ~108,smaller sub-threshold swing(SS) of 0.07 V decade-1,and a negligible threshold voltage shift(ΔVTH) of 0.08 V under positive bias stress(PBS) for 7200 s.To confirm its potential application in logic circuit,a resistor-loaded inverter based on HGO/α-IGZO TFTs has been constructed.A high voltage gain of 19.8 and stable full swing characteristics have been detected.As a result,it can be concluded that aqueous-solution-driven HGO dielectrics have potential application in high resolution flat panel displays and ultra-large-scale integrated logic circuits.展开更多
LiYF_4 nanocrystals with tetragonal structure were adopted as the host materials for the phosphors and scintillators owing to the low phonon energy and high optical transparency. LiYF_4：Ln^（3＋）（Ce^（3＋）,Eu^（3...LiYF_4 nanocrystals with tetragonal structure were adopted as the host materials for the phosphors and scintillators owing to the low phonon energy and high optical transparency. LiYF_4：Ln^（3＋）（Ce^（3＋）,Eu^（3＋）） nanocrystals were fabricated by solvothermal method. Under UV excitation, they could emit visible light. In order to improve the luminescence intensity, the method of co-doping LiYF_4 nanocrystals with Sc was adopted. Sc^（3＋） ions could reduce the lattice expansion caused by the doping of Ce^（3＋） or Eu^（3＋） whose ionic radius was larger than Y^（3＋）. Crystal structure of Li（Y,Sc）F_4：Ln^（3＋） kept much more stable and the luminescence intensity could be significantly enhanced when the concentration of Sc was a moderate value. Thermoluminescence was employed to analyze the electron traps in Li（Y,Sc）F_4：Ce^（3＋）. Results suggested that the suppression of the generation of electron traps with the co-doping of Sc contributed to the enhancement of luminescence intensity of LiYF_4：Ce^（3＋）.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 11774001 and 51572002)Open fund for Discipline Construction, Institute of Physical Science and Information Technology, Anhui University (No. S01003101)。
文摘In this work,a non-toxic and environmentally friendly aqueous-solution-based method has been adopted to prepare gadolinium-doped hafnium oxide(HfO2) gate dielectric thin films.By adjusting the gadolinium(Gd) doping concentration,the oxygen vacancy content,band offset,interface trap density,and dielectric constant of HfGdOx(HGO) thin films have been optimized.Results have confirmed that HGO thin films with Gd doping ratio of 15 at.% have demonstrated appropriate dielectric constant of 27.1 and lower leakage current density of 5.8×10-9 A cm-2.Amorphous indium-gallium-zinc oxide(α-IGZO) thin film transistors(TFTs) based on HGO thin film(Gd:15 at.%) as gate dielectric layer have exhibited excellent electrical performance,such as larger saturated carrier mobility(μsat) of 20.1 cm2 V-1 S-1,high on/off current ratio(Ion/Ioff) of ~108,smaller sub-threshold swing(SS) of 0.07 V decade-1,and a negligible threshold voltage shift(ΔVTH) of 0.08 V under positive bias stress(PBS) for 7200 s.To confirm its potential application in logic circuit,a resistor-loaded inverter based on HGO/α-IGZO TFTs has been constructed.A high voltage gain of 19.8 and stable full swing characteristics have been detected.As a result,it can be concluded that aqueous-solution-driven HGO dielectrics have potential application in high resolution flat panel displays and ultra-large-scale integrated logic circuits.
基金supported by the National Natural Science Foundation of China(51171239)Shanghai University Innovation Program
文摘LiYF_4 nanocrystals with tetragonal structure were adopted as the host materials for the phosphors and scintillators owing to the low phonon energy and high optical transparency. LiYF_4：Ln^（3＋）（Ce^（3＋）,Eu^（3＋）） nanocrystals were fabricated by solvothermal method. Under UV excitation, they could emit visible light. In order to improve the luminescence intensity, the method of co-doping LiYF_4 nanocrystals with Sc was adopted. Sc^（3＋） ions could reduce the lattice expansion caused by the doping of Ce^（3＋） or Eu^（3＋） whose ionic radius was larger than Y^（3＋）. Crystal structure of Li（Y,Sc）F_4：Ln^（3＋） kept much more stable and the luminescence intensity could be significantly enhanced when the concentration of Sc was a moderate value. Thermoluminescence was employed to analyze the electron traps in Li（Y,Sc）F_4：Ce^（3＋）. Results suggested that the suppression of the generation of electron traps with the co-doping of Sc contributed to the enhancement of luminescence intensity of LiYF_4：Ce^（3＋）.
