SrZnO2 ： Eu^3 ＋ , Li^＋ phosphor powder by long wavelength UV excitation was synthesized by conventional solid-state reaction method. XRD and PL were employed to characterize their properties. The resuits show that ...SrZnO2 ： Eu^3 ＋ , Li^＋ phosphor powder by long wavelength UV excitation was synthesized by conventional solid-state reaction method. XRD and PL were employed to characterize their properties. The resuits show that Eu^3＋ ions preferentially occupy Sr^2＋ asymmetry cationic sites, thus emitting 612 nm red light originated from ^5D0 to ^7F2 transition. The luminescent intensity can be greatly enhanced with incorporation of Li^＋ ions. The excitation efficiency in range of 350 - 400 nm also increases greatly due to incorporating Li ^＋ ions. SrZnO2 ： Eu^3 ＋ , Li^＋ is a promising redemitting phosphor by long wavelength UV excitation.展开更多
A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15...A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.展开更多
InAs0.052Sb0.948 epilayers with cutoff wavelengths longer than 8 μm were successfully grown on InAs substrates using melt epitaxy （ME）. Scanning electron microscopy observations show that the interface between the ...InAs0.052Sb0.948 epilayers with cutoff wavelengths longer than 8 μm were successfully grown on InAs substrates using melt epitaxy （ME）. Scanning electron microscopy observations show that the interface between the epilayers and substrates is flat, indicating the good quality of the epilayers, and the thickness of the epilayers is 40 μm. Photoconductors were fabricated using InAs0.052Sb0.948 thick epilayers grown by ME. Ge optical lenses were set on the photoconductors. At room temperature, the photoresponse wavelength range was 2-10μm. The peak detectivity Dλp reached 5.4 × 10^9 cm-Hz^1/2.W^-1 for the immersed detectors. The detectivity D^＊ was 9.3 × 10^8 and 1.3 × 10^8 cm.Hz^1/2.W^-1 at the wavelength of 8 and 9 μm, respectively. The good performance of the uncooled InAsSb detectors was experimentally validated.展开更多
The etching and passivation processes of very long wavelength infrared(VLWIR)detector based on the InAs/GaSb/AlSb type-II superlattice have been studied.By studying the effect of each component in the citric acid solu...The etching and passivation processes of very long wavelength infrared(VLWIR)detector based on the InAs/GaSb/AlSb type-II superlattice have been studied.By studying the effect of each component in the citric acid solution(citric acid,phosphoric acid,hydrogen peroxide,deionized water),the best solution ratio is obtained.After comparing different passivation materials such as sulfide+SiO_(2),Al_(2)O_(3),Si_(3)N_(4) and SU8,it is found that SU8 passivation can reduce the dark current of the device to a greater degree.Combining this wet etching and SU8 passivation,the of VLWIR detector with a mesa diameter of 500μm is about 3.6Ω·cm^(2) at 77 K.展开更多
We report on a long wavelength interband cascade photodetector with type Ⅱ InAs/GaSb superlattice absorber.The device is a three-stage interband cascade structure.At 77 K,the 50%cutoff wavelength of the detector is 8...We report on a long wavelength interband cascade photodetector with type Ⅱ InAs/GaSb superlattice absorber.The device is a three-stage interband cascade structure.At 77 K,the 50%cutoff wavelength of the detector is 8.48μm and the peak photoresponse wavelength is 7.78μm.The peak responsivity is 0.93 A/W and the detectivity D*is 1.12×10^(11)cm·Hz0.5/W for 7.78μm at-0.20 V.The detector can operate up to about 260 K.At 260 K,the 50%cutoff wavelength is 11.52μm,the peak responsivity is 0.78 A/W and the D*is 5.02×10^(8)cm·Hz0.5/W for the peak wavelength of 10.39μm at-2.75 V.The dark current of the device is dominated by the diffusion current under both a small bias voltage of-0.2 V and a large one of-2.75 V for the temperature range of 120 to 260 K.展开更多
In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 2...In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 24.5 GHz and then abruptly fall. In 100 nm base width, we have 17.5 GHz cut off frequency, and overall ac performances become optimized, although, other parameters like optical losses and threshold current density are not optimized.展开更多
On account of the advantages of organic electroluminescent materials compared with their inorganic counterparts,the development of organic electroluminescent materials is one of the hot areas of the optoelectronic mat...On account of the advantages of organic electroluminescent materials compared with their inorganic counterparts,the development of organic electroluminescent materials is one of the hot areas of the optoelectronic materials.Fluorene and its derivatives,which have an aromatic biphenyl structure with a wide energy gap in the backbones and high luminescent efficiency,have drawn much attention of ma-terial chemists and device physicists.However,one drawback of fluorene-based electroluminescent blue materials is that there is an occurrence of long wavelength emission after annealing the films in air or after operating organic light-emitting diodes for a long time.To clarify the origin of this long wave-length emission,the scientists at home and abroad have put forward all kinds of correlative explana-tions.Among the scientists,some thought it was caused by excimer-related species,while some others claimed that it was caused by the fluorenone of photooxdized fluorene.The corresponding solutions to this problem have also been proposed and the problem has been partially resolved in some degree.The present review summarizes and analyzes the progress made on the origin of long wavelength emission in fluorene-based electroluminescent blue materials at home and abroad in the past few years.Some issues to be addressed and hotspots to be further investigated are also presented and discussed.展开更多
Infrared detection technology has greatly expanded the ability of mankind to study the earth and the universe. In recent years, the demand for long-wavelength infrared detectors is increasing for their advantages in e...Infrared detection technology has greatly expanded the ability of mankind to study the earth and the universe. In recent years, the demand for long-wavelength infrared detectors is increasing for their advantages in exploring the earth and the universe. A variety of long-wavelength infrared detectors have been made based on thermal resistive effect, photoelectric effect, etc., in the past few decades. Remarkable achievements have been made in infrared materials, device fabrication,readout circuit, and device package. However, high performance long-wavelength infrared detectors, especially those for large format long-wavelength infrared detector focus plane array, are still unsatisfactory. Low noise, high detectivity, and large format long-wavelength infrared detector is necessary to satisfy space-based application requirements.展开更多
Strontium aluminate long persistence phos phors are synthesized by combustion method. By control- ling the raw material ratio （Sr/Al）, the effects of phase composition on subsequent spectroscopic properties of phosp...Strontium aluminate long persistence phos phors are synthesized by combustion method. By control- ling the raw material ratio （Sr/Al）, the effects of phase composition on subsequent spectroscopic properties of phosphors are studied. Results show that the phase com-position changes from strontium-rich phase to aluminum- rich phase with the decrease of Sr/AI： when the rate of Al/Sr changes from 3：1 to 1：1, the main crystal phase of samples is Sr3Al206, and it exhibits the characteristic fluorescence of Eu^3＋ in the lattice of Sr3Al206; when the rate of Al/Sr is between 1：2 and 2：7, phase composition is the mixture of SrAl204 and SrAl4OT, and it emits the characteristic fluorescence of Eu^2＋ in SrAl204 but not in SrAl4OT; when Al/Sr decreases to 1：4 or even 1：12, the main crystal phase of samples transform into SrAl12019, and the characteristic emission peak is about 470 nm, which corresponds to the characteristic emission of Eu2＋ in SrAl12019. At the end of the article, the influence laws of two different synthesis methods on phase composition of samples between high-temperature solid method and combustion method are compared. Compared with the high-temperature solid method, the rule of influence is similar, but the mole ratio of Al/Sr in products is always higher than the initial ratio of the raw material, and com-pounds like Sr4Al14025 are not obtained by combustion method.展开更多
锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角...锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。展开更多
文摘SrZnO2 ： Eu^3 ＋ , Li^＋ phosphor powder by long wavelength UV excitation was synthesized by conventional solid-state reaction method. XRD and PL were employed to characterize their properties. The resuits show that Eu^3＋ ions preferentially occupy Sr^2＋ asymmetry cationic sites, thus emitting 612 nm red light originated from ^5D0 to ^7F2 transition. The luminescent intensity can be greatly enhanced with incorporation of Li^＋ ions. The excitation efficiency in range of 350 - 400 nm also increases greatly due to incorporating Li ^＋ ions. SrZnO2 ： Eu^3 ＋ , Li^＋ is a promising redemitting phosphor by long wavelength UV excitation.
基金supported by the National Basic Research Program of China(Grant Nos.2013CB932904 and 2011CB922201)the National Special Funds for the Development of Major Research Equipment and Instruments,China(Grant No.2012YQ140005)the National Natural Science Foundation of China(Grant Nos.61274013,61290303,and 61306013)
文摘A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.
基金financially supported by the National Natural Science Foundation of China (No. 60777022)the Fundamental Research Funds for the Central Universities
文摘InAs0.052Sb0.948 epilayers with cutoff wavelengths longer than 8 μm were successfully grown on InAs substrates using melt epitaxy （ME）. Scanning electron microscopy observations show that the interface between the epilayers and substrates is flat, indicating the good quality of the epilayers, and the thickness of the epilayers is 40 μm. Photoconductors were fabricated using InAs0.052Sb0.948 thick epilayers grown by ME. Ge optical lenses were set on the photoconductors. At room temperature, the photoresponse wavelength range was 2-10μm. The peak detectivity Dλp reached 5.4 × 10^9 cm-Hz^1/2.W^-1 for the immersed detectors. The detectivity D^＊ was 9.3 × 10^8 and 1.3 × 10^8 cm.Hz^1/2.W^-1 at the wavelength of 8 and 9 μm, respectively. The good performance of the uncooled InAsSb detectors was experimentally validated.
基金supported by the National Basic Research Program of China(Grant Nos.2018YFA0209102 and 2019YFA070104)the National Natural Science Foundation of China(Grant Nos.61790581 and 61274013)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB22)。
文摘The etching and passivation processes of very long wavelength infrared(VLWIR)detector based on the InAs/GaSb/AlSb type-II superlattice have been studied.By studying the effect of each component in the citric acid solution(citric acid,phosphoric acid,hydrogen peroxide,deionized water),the best solution ratio is obtained.After comparing different passivation materials such as sulfide+SiO_(2),Al_(2)O_(3),Si_(3)N_(4) and SU8,it is found that SU8 passivation can reduce the dark current of the device to a greater degree.Combining this wet etching and SU8 passivation,the of VLWIR detector with a mesa diameter of 500μm is about 3.6Ω·cm^(2) at 77 K.
基金supported in part by China’s NSF Program 61874103
文摘We report on a long wavelength interband cascade photodetector with type Ⅱ InAs/GaSb superlattice absorber.The device is a three-stage interband cascade structure.At 77 K,the 50%cutoff wavelength of the detector is 8.48μm and the peak photoresponse wavelength is 7.78μm.The peak responsivity is 0.93 A/W and the detectivity D*is 1.12×10^(11)cm·Hz0.5/W for 7.78μm at-0.20 V.The detector can operate up to about 260 K.At 260 K,the 50%cutoff wavelength is 11.52μm,the peak responsivity is 0.78 A/W and the D*is 5.02×10^(8)cm·Hz0.5/W for the peak wavelength of 10.39μm at-2.75 V.The dark current of the device is dominated by the diffusion current under both a small bias voltage of-0.2 V and a large one of-2.75 V for the temperature range of 120 to 260 K.
文摘In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 24.5 GHz and then abruptly fall. In 100 nm base width, we have 17.5 GHz cut off frequency, and overall ac performances become optimized, although, other parameters like optical losses and threshold current density are not optimized.
基金the National Natural Science Foundation of China(Grant Nos:90406021,20774043and20574012)Natural Science Foundation of Jiangsu College Council(Grant No:KJD150148)Scientific Research Foundation of Nanjing University of Posts and Telecommunications(Grant No:NY206069)
文摘On account of the advantages of organic electroluminescent materials compared with their inorganic counterparts,the development of organic electroluminescent materials is one of the hot areas of the optoelectronic materials.Fluorene and its derivatives,which have an aromatic biphenyl structure with a wide energy gap in the backbones and high luminescent efficiency,have drawn much attention of ma-terial chemists and device physicists.However,one drawback of fluorene-based electroluminescent blue materials is that there is an occurrence of long wavelength emission after annealing the films in air or after operating organic light-emitting diodes for a long time.To clarify the origin of this long wave-length emission,the scientists at home and abroad have put forward all kinds of correlative explana-tions.Among the scientists,some thought it was caused by excimer-related species,while some others claimed that it was caused by the fluorenone of photooxdized fluorene.The corresponding solutions to this problem have also been proposed and the problem has been partially resolved in some degree.The present review summarizes and analyzes the progress made on the origin of long wavelength emission in fluorene-based electroluminescent blue materials at home and abroad in the past few years.Some issues to be addressed and hotspots to be further investigated are also presented and discussed.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51502337)the Fund from China Academy of Space Technology
文摘Infrared detection technology has greatly expanded the ability of mankind to study the earth and the universe. In recent years, the demand for long-wavelength infrared detectors is increasing for their advantages in exploring the earth and the universe. A variety of long-wavelength infrared detectors have been made based on thermal resistive effect, photoelectric effect, etc., in the past few decades. Remarkable achievements have been made in infrared materials, device fabrication,readout circuit, and device package. However, high performance long-wavelength infrared detectors, especially those for large format long-wavelength infrared detector focus plane array, are still unsatisfactory. Low noise, high detectivity, and large format long-wavelength infrared detector is necessary to satisfy space-based application requirements.
基金financially supported by the National Natural Science Foundation of China(No.NSFC50962001)the Scientific Research Foundation of Beifang Ethnic University for Nationalities(No.2010Y042)
文摘Strontium aluminate long persistence phos phors are synthesized by combustion method. By control- ling the raw material ratio （Sr/Al）, the effects of phase composition on subsequent spectroscopic properties of phosphors are studied. Results show that the phase com-position changes from strontium-rich phase to aluminum- rich phase with the decrease of Sr/AI： when the rate of Al/Sr changes from 3：1 to 1：1, the main crystal phase of samples is Sr3Al206, and it exhibits the characteristic fluorescence of Eu^3＋ in the lattice of Sr3Al206; when the rate of Al/Sr is between 1：2 and 2：7, phase composition is the mixture of SrAl204 and SrAl4OT, and it emits the characteristic fluorescence of Eu^2＋ in SrAl204 but not in SrAl4OT; when Al/Sr decreases to 1：4 or even 1：12, the main crystal phase of samples transform into SrAl12019, and the characteristic emission peak is about 470 nm, which corresponds to the characteristic emission of Eu2＋ in SrAl12019. At the end of the article, the influence laws of two different synthesis methods on phase composition of samples between high-temperature solid method and combustion method are compared. Compared with the high-temperature solid method, the rule of influence is similar, but the mole ratio of Al/Sr in products is always higher than the initial ratio of the raw material, and com-pounds like Sr4Al14025 are not obtained by combustion method.
文摘锗是重要的红外光学材料,为减小锗表面的菲涅耳反射损耗,提高光利用率,研究了锗基底圆锥形微结构的减反射性能。基于时域有限差分法(Finite Difference Time Domain),并采用单因素法研究了微结构的占空比、周期、高度等结构参数与入射角在8~12μm长波红外波段对反射率的影响,确定了微结构在低反射情况下较优的结构参数组合,其在整个波段范围内的平均反射率低于1%,远低于平板锗结构的35.47%,在9~11μm的波段范围内反射率低于0.5%,且光波在40°范围内入射时,圆锥形微结构的平均反射率仍然较低。将优化的圆锥形微结构与平板结构进行了对比,从等效折射率、反射场分布和能量吸收分布3方面进一步证实了圆锥形微结构在整个波段范围内优异的减反射性能。
