We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar...We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar due to the large difference between the compressibility of the SiO2 matrix and Si substrate. The observed effect can be understood by the nonhomogeneous distribution of the elastic field in the Ge/SiO2/Si nanosystem. Previous high pressure PL results on the Si/SiO2/Si nanosystem can also be explained by the nonuniform distribution of the elastic field. Although our investigation focuses on the Ge/SiO2/Si nanosystem, our results could provide generally understanding on the elastic properties of different multi-component nanosystems.展开更多
SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special ph...SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special photoluminescence property and exhibit strong luminescence at 392 nm（3.12 eV）, secondary strong luminescence at 600 nm（2.05 eV） and weak luminescence at 770 nm（1.60 eV） when excited under 246 nm（5.01 eV） ultra-violet light at room temperature. The structure of this new luminescence material was studied with XRD, XPS, and TEM. The results show that the presence of nanometer sized（around 10 nm） Ge and GeO crystals in the SiO2 may cause the three-band photoluminescence. The GeO2/SiO2 glass without going through the reducing process only has GeO2 in the SiO2 glass, and does not show the photo-（luminescence）.展开更多
The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structur...The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structures of Ge（SiO2）n are obtained by adding one Ge on the end site of the O atom or the Si near end site of the O atom in（SiO2）n.The chemical activation of Ge-（SiO2）n is improved compared with（SiO2）n.The calculated second-order difference of energies and fragmentation energies show that the Ge（SiO2）n clusters with n = 2 or 5 are stable.展开更多
Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal- oxide-semiconductor transistors and efficient photonic devices. In this paper, we design the Ge...Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal- oxide-semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si3N4 or SiO？ for improving their tensile strain and simulate the strain profiles by using the finite difference time domain （FDTD） method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si3N4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices.展开更多
Ge-SiO2 thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO2 composite target. Films were annealed in N2 ambience for 30 min at 300℃-1000℃ wi...Ge-SiO2 thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO2 composite target. Films were annealed in N2 ambience for 30 min at 300℃-1000℃ with an interval of 100℃. Through the X-ray diffraction, the average size of Ge nanocrystals (nc-Ge) was determined. They increased from 3.9 to 6.1 nm with increasing annealing temperature in the range of 600℃-1000℃. Under ultraviolet excitation, all samples emit a strong violet band centered at 396 nm. With the formation of nc-Ge, the samples exhibit another emission of orange band with the peak at 580 nm and its intensity increases with the increasing size of nc-Ge.The peak positions of two bands do not shift obviously. Experimental data indicate that the violet band comes from GeO defect and the orange band originates mainly from the luminescence centers at the interface between the nc-Ge and SiO2 matrix.展开更多
The structural and optical properties of semiconductor microcrystals embedded in glassy thin films have prompted considerable interest in the fields of solid state physics and materials science. They are currently sub...The structural and optical properties of semiconductor microcrystals embedded in glassy thin films have prompted considerable interest in the fields of solid state physics and materials science. They are currently subjects of intensive research for both fundamental and practical reasons. Since the semiconductor-embedded glassy films show distinctive optical properties, many studies have been carried out to evaluate the usefulness of this type展开更多
文摘We report the pressure dependence of Ge nanocrystals embedded in SiO2 film matrix on Si substrate using Raman scattering and finite element analysis. Delamination of SiO2 film from the Si substrate occurs at ～23 kbar due to the large difference between the compressibility of the SiO2 matrix and Si substrate. The observed effect can be understood by the nonhomogeneous distribution of the elastic field in the Ge/SiO2/Si nanosystem. Previous high pressure PL results on the Si/SiO2/Si nanosystem can also be explained by the nonuniform distribution of the elastic field. Although our investigation focuses on the Ge/SiO2/Si nanosystem, our results could provide generally understanding on the elastic properties of different multi-component nanosystems.
文摘SiO2 glassy materials with Ge crystals embedded were formed by heating GeO2/SiO2 glass at 700 in the presence of hydrogen. GeO2/SiO2 glass was prepared with the sol-gel technique. The Ge/SiO2 samples show a special photoluminescence property and exhibit strong luminescence at 392 nm（3.12 eV）, secondary strong luminescence at 600 nm（2.05 eV） and weak luminescence at 770 nm（1.60 eV） when excited under 246 nm（5.01 eV） ultra-violet light at room temperature. The structure of this new luminescence material was studied with XRD, XPS, and TEM. The results show that the presence of nanometer sized（around 10 nm） Ge and GeO crystals in the SiO2 may cause the three-band photoluminescence. The GeO2/SiO2 glass without going through the reducing process only has GeO2 in the SiO2 glass, and does not show the photo-（luminescence）.
基金Project supported by the foundation start up for high level talents of Shihezi university (No. RCZX200747)
文摘The geometry,stability,binding energy and electronic properties of（SiO2）n and Ge（SiO2）n clusters（n = 7） have been investigated by Density functional theory（DFT）.The results show that the lowest energy structures of Ge（SiO2）n are obtained by adding one Ge on the end site of the O atom or the Si near end site of the O atom in（SiO2）n.The chemical activation of Ge-（SiO2）n is improved compared with（SiO2）n.The calculated second-order difference of energies and fragmentation energies show that the Ge（SiO2）n clusters with n = 2 or 5 are stable.
基金Project supported by the National Basic Research Program of China (Grant Nos.2012CB933503 and 2013CB632103)the National Natural Science Foundation of China (Grant Nos.61176092,61036003,and 60837001)+1 种基金the Ph.D.Program Foundation of the Ministry of Education of China (Grant No.20110121110025)the Fundamental Research Funds for the Central Universities,China (Grant No.2010121056)
文摘Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal- oxide-semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si3N4 or SiO？ for improving their tensile strain and simulate the strain profiles by using the finite difference time domain （FDTD） method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si3N4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices.
基金This work was supported by Ion Beam Laboratory, Shanghai Institute of Metallurgy, Chinese Academy of Sciences.
文摘Ge-SiO2 thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO2 composite target. Films were annealed in N2 ambience for 30 min at 300℃-1000℃ with an interval of 100℃. Through the X-ray diffraction, the average size of Ge nanocrystals (nc-Ge) was determined. They increased from 3.9 to 6.1 nm with increasing annealing temperature in the range of 600℃-1000℃. Under ultraviolet excitation, all samples emit a strong violet band centered at 396 nm. With the formation of nc-Ge, the samples exhibit another emission of orange band with the peak at 580 nm and its intensity increases with the increasing size of nc-Ge.The peak positions of two bands do not shift obviously. Experimental data indicate that the violet band comes from GeO defect and the orange band originates mainly from the luminescence centers at the interface between the nc-Ge and SiO2 matrix.
基金Project supported by the National Natural Science Foundation of China
文摘The structural and optical properties of semiconductor microcrystals embedded in glassy thin films have prompted considerable interest in the fields of solid state physics and materials science. They are currently subjects of intensive research for both fundamental and practical reasons. Since the semiconductor-embedded glassy films show distinctive optical properties, many studies have been carried out to evaluate the usefulness of this type
