First-principles calculations have been performed to clarify the differences of the electronic structures of Ga-doped ZnO and ZnS. Results show the local density approximation and local density approximation＋U calcul...First-principles calculations have been performed to clarify the differences of the electronic structures of Ga-doped ZnO and ZnS. Results show the local density approximation and local density approximation＋U calculations are in good qualitative agreement with each other. After doping, impurity states appear near the Fermi level in both ZnO and ZnS cases. When ZnO is doped, the impurity states are delocalized in the whole conduction band. On the contrary, when ZnS is doped, though the p state of Ga is also delocalized, the s state is localized near the Fermi level. Partial charge density distributions of the frontier orbital show the same information. After an exchange of the crystal structures of ZnO and ZnS, results remain unchanged. The localized Ga s state accounts for the bad electrical properties of Ga-doped ZnS.展开更多
A photoanode with Ga-doped ZnO nanorods has been prepared on F-doped SnO2 (FTO) coated glass substrate and its application in dye-sensitized solar cells (DSSCs) has been investigated. Ga-doped ZnO nanorods have been s...A photoanode with Ga-doped ZnO nanorods has been prepared on F-doped SnO2 (FTO) coated glass substrate and its application in dye-sensitized solar cells (DSSCs) has been investigated. Ga-doped ZnO nanorods have been synthesized by an electric-field-assisted wet chemical approach at 80?C. Under a direct current electric field, the nanorods predominantly grow on cathodes. The results of the X-ray photoelectron spectroscopy and photoluminescence verify that Ga dopant is successfully incorporated into the ZnO wurtzite lattice structure. Finally, employing Ga-doped ZnO nanorods with the length of ~5 μm as the photoanode of DSSCs, an overall energy conversion efficiency of 2.56% is achieved. The dramatically improved performance of Ga-doped ZnO based DSSCs compared with that of pure ZnO is due to the higher electron conductivity.展开更多
Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Co...Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Consequently,we comparatively studied the doped thin films on the basis of their structural,morphological,electrical,and optical properties for optoelectronic applications.Both thin films exhibited excellent optical properties with more than 85%transmission in the visible range.The GZO thin film had better crystallinity and smoother surface morphology than the AZO thin film.The conductivity of the GZO thin film was improved compared to that of the AZO thin film：the resistivity decreased from 1.01×10^-3 to 3.5×10^-4 Ω cm,which was mostly due to the increase of the carrier concentration from 6.5×10^20 to 1.46×10^21cm^-3.These results revealed that the GZO thin film had higher quality than the AZO thin film with the same doping concentration for optoelectronic applications.展开更多
In the present study,a simple method for the preparation of a luminescent flexible gallium doped zinc oxide(GZO)/polystyrene nanocomposite film was developed.The prepared GZO powder was characterized through different...In the present study,a simple method for the preparation of a luminescent flexible gallium doped zinc oxide(GZO)/polystyrene nanocomposite film was developed.The prepared GZO powder was characterized through different optical and structural techniques.The XRD study revealed the existence of a wurtzite structure with no extra oxide peaks.Elemental-mapping,EDX,FTIR and XPS analyses were used to confirm the presence of elements and the several groups present in the structure.Under excitations of UV,the prepared hybrid nanocomposite showed a strong cyan emission with narrow full width at half the maximum value(20 nm)that has not been reported before.X-ray and laser-induced luminescence results of the hy-brid film revealed novel blue-green emission at room temperature.The prepared composite film showed a strong scintillation re-sponse to ionizing radiation.The strong emissions,very weak deep-level emissions,and low FWHM of composite indicate the de-sirable optical properties with low-density structural defects in the GZO composite structure.Therefore,the prepared hybrid film can be considered to be a suitable candidate for the fabrication of optoelectronic devices.展开更多
Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivit...Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.展开更多
C-axis oriented Ga-doped ZnO(GZO) films with various thicknesses were deposited on glass substrate by radio frequency(RF) magnetron sputtering. The dependence of crystal structure,electrical,and optical properties of ...C-axis oriented Ga-doped ZnO(GZO) films with various thicknesses were deposited on glass substrate by radio frequency(RF) magnetron sputtering. The dependence of crystal structure,electrical,and optical properties of the GZO films on crystalline size were systematically studied. The results showed that the texture coefficient of (002) peak (TC(002)) decreases with increasing crystalline size. The Hall mobility m was reciprocal to electron effective mass and the fitted relaxation time s was 0.11±0.01 ms. With the increase of average crystalline size,the resistivity increased slightly,which is caused by the competition of (002) and(101) plane,introducing in some defects and leading to carrier density reduction. The optical band gap was in the range from 3.454 to 3.319 eV with increasing crystalline size from 26.96 to 30.88 nm,showing a negative relationship. The dependence of optical band gap (Eopg) on the crystalline size(R) can be qualitatively explained by a quantum confinement effect. The relationship between Eopg and R of GZO films suggests that tuning up optical properties for desired applications can be achieved by controlling the crystalline size.展开更多
An 8μm thick Ga-doped ZnO（GZO） film grown by metal-source vapor phase epitaxy was deposited on a GaN-based light-emitting diode（LED） to substitute for the conventional ITO as a transparent conduct layer（TCL）. E...An 8μm thick Ga-doped ZnO（GZO） film grown by metal-source vapor phase epitaxy was deposited on a GaN-based light-emitting diode（LED） to substitute for the conventional ITO as a transparent conduct layer（TCL）. Electroluminescence spectra exhibited that the intensity value of LED emission with a GZO TCL is markedly improved by 23.6%as compared to an LED with an ITO TCL at 20 mA.In addition,the forward voltage of the LED with a GZO TCL at 20 mA is higher than that of the conventional LED.To investigate the reason for the increase of the forward voltage,X-ray photoelectron spectroscopy was performed to analyze the interface properties of the GZO/p-GaN heterojunction.The large valence band offset（2.24±0.21 eV） resulting from the formation of Ga_2O_3 in the GZO/p-GaN interface was attributed to the increase of the forward voltage.展开更多
Gallium （Ga）-doped ZnO is regarded as a promising plasmonic material with a wide range of applications in plasmonics. In this study, zinc self-diffusion experiments are adopted to disclose the nature of the dominant...Gallium （Ga）-doped ZnO is regarded as a promising plasmonic material with a wide range of applications in plasmonics. In this study, zinc self-diffusion experiments are adopted to disclose the nature of the dominant compensating defect in Ga-doped ZnO isotopic heterostructures. The （GaZn-VZ.）- complex defect, instead of the isolated VZn^2-, is identified as the predominant compensating acceptor center responsible for the low donor doping efficiency. The comparative diffusion experiments operated by the secondary ion mass spectrometry reveal a -0.78 eV binding energy of this complex defect, which well matches the electrical activation energy derived from the temperature-dependent Hall effect measurements （-（0.82±0.02） eV）. These findings contribute to an essential understanding of the （GaZn-VZn）- complex defect and the potential engineering routes of heavily Ga-doped ZnO.展开更多
文摘First-principles calculations have been performed to clarify the differences of the electronic structures of Ga-doped ZnO and ZnS. Results show the local density approximation and local density approximation＋U calculations are in good qualitative agreement with each other. After doping, impurity states appear near the Fermi level in both ZnO and ZnS cases. When ZnO is doped, the impurity states are delocalized in the whole conduction band. On the contrary, when ZnS is doped, though the p state of Ga is also delocalized, the s state is localized near the Fermi level. Partial charge density distributions of the frontier orbital show the same information. After an exchange of the crystal structures of ZnO and ZnS, results remain unchanged. The localized Ga s state accounts for the bad electrical properties of Ga-doped ZnS.
文摘A photoanode with Ga-doped ZnO nanorods has been prepared on F-doped SnO2 (FTO) coated glass substrate and its application in dye-sensitized solar cells (DSSCs) has been investigated. Ga-doped ZnO nanorods have been synthesized by an electric-field-assisted wet chemical approach at 80?C. Under a direct current electric field, the nanorods predominantly grow on cathodes. The results of the X-ray photoelectron spectroscopy and photoluminescence verify that Ga dopant is successfully incorporated into the ZnO wurtzite lattice structure. Finally, employing Ga-doped ZnO nanorods with the length of ~5 μm as the photoanode of DSSCs, an overall energy conversion efficiency of 2.56% is achieved. The dramatically improved performance of Ga-doped ZnO based DSSCs compared with that of pure ZnO is due to the higher electron conductivity.
基金Funded by National Natural Science Foundation of China(NSFC)(Nos.21205127,61275114)
文摘Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Consequently,we comparatively studied the doped thin films on the basis of their structural,morphological,electrical,and optical properties for optoelectronic applications.Both thin films exhibited excellent optical properties with more than 85%transmission in the visible range.The GZO thin film had better crystallinity and smoother surface morphology than the AZO thin film.The conductivity of the GZO thin film was improved compared to that of the AZO thin film：the resistivity decreased from 1.01×10^-3 to 3.5×10^-4 Ω cm,which was mostly due to the increase of the carrier concentration from 6.5×10^20 to 1.46×10^21cm^-3.These results revealed that the GZO thin film had higher quality than the AZO thin film with the same doping concentration for optoelectronic applications.
基金the Iranian National Elites Foundation for the financial support of this research
文摘In the present study,a simple method for the preparation of a luminescent flexible gallium doped zinc oxide(GZO)/polystyrene nanocomposite film was developed.The prepared GZO powder was characterized through different optical and structural techniques.The XRD study revealed the existence of a wurtzite structure with no extra oxide peaks.Elemental-mapping,EDX,FTIR and XPS analyses were used to confirm the presence of elements and the several groups present in the structure.Under excitations of UV,the prepared hybrid nanocomposite showed a strong cyan emission with narrow full width at half the maximum value(20 nm)that has not been reported before.X-ray and laser-induced luminescence results of the hy-brid film revealed novel blue-green emission at room temperature.The prepared composite film showed a strong scintillation re-sponse to ionizing radiation.The strong emissions,very weak deep-level emissions,and low FWHM of composite indicate the de-sirable optical properties with low-density structural defects in the GZO composite structure.Therefore,the prepared hybrid film can be considered to be a suitable candidate for the fabrication of optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China (Grant No.52171221)the National Key Research and Development Program of China (Grant No.2019YFA0704900)。
文摘Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.
基金supported by the National Natural Science Foundation of China (No.51071038)Sichuan Province Science Foundation for Youths (No.2010JQ0002)State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,China (No.20131309)
文摘C-axis oriented Ga-doped ZnO(GZO) films with various thicknesses were deposited on glass substrate by radio frequency(RF) magnetron sputtering. The dependence of crystal structure,electrical,and optical properties of the GZO films on crystalline size were systematically studied. The results showed that the texture coefficient of (002) peak (TC(002)) decreases with increasing crystalline size. The Hall mobility m was reciprocal to electron effective mass and the fitted relaxation time s was 0.11±0.01 ms. With the increase of average crystalline size,the resistivity increased slightly,which is caused by the competition of (002) and(101) plane,introducing in some defects and leading to carrier density reduction. The optical band gap was in the range from 3.454 to 3.319 eV with increasing crystalline size from 26.96 to 30.88 nm,showing a negative relationship. The dependence of optical band gap (Eopg) on the crystalline size(R) can be qualitatively explained by a quantum confinement effect. The relationship between Eopg and R of GZO films suggests that tuning up optical properties for desired applications can be achieved by controlling the crystalline size.
文摘An 8μm thick Ga-doped ZnO（GZO） film grown by metal-source vapor phase epitaxy was deposited on a GaN-based light-emitting diode（LED） to substitute for the conventional ITO as a transparent conduct layer（TCL）. Electroluminescence spectra exhibited that the intensity value of LED emission with a GZO TCL is markedly improved by 23.6%as compared to an LED with an ITO TCL at 20 mA.In addition,the forward voltage of the LED with a GZO TCL at 20 mA is higher than that of the conventional LED.To investigate the reason for the increase of the forward voltage,X-ray photoelectron spectroscopy was performed to analyze the interface properties of the GZO/p-GaN heterojunction.The large valence band offset（2.24±0.21 eV） resulting from the formation of Ga_2O_3 in the GZO/p-GaN interface was attributed to the increase of the forward voltage.
基金supported by the National Natural Science Foundation of China(Grants Nos.11674405,and 11675280)
文摘Gallium （Ga）-doped ZnO is regarded as a promising plasmonic material with a wide range of applications in plasmonics. In this study, zinc self-diffusion experiments are adopted to disclose the nature of the dominant compensating defect in Ga-doped ZnO isotopic heterostructures. The （GaZn-VZ.）- complex defect, instead of the isolated VZn^2-, is identified as the predominant compensating acceptor center responsible for the low donor doping efficiency. The comparative diffusion experiments operated by the secondary ion mass spectrometry reveal a -0.78 eV binding energy of this complex defect, which well matches the electrical activation energy derived from the temperature-dependent Hall effect measurements （-（0.82±0.02） eV）. These findings contribute to an essential understanding of the （GaZn-VZn）- complex defect and the potential engineering routes of heavily Ga-doped ZnO.
