共查询到20条相似文献,搜索用时 390 毫秒
1.
Xianglong Zeng Xianfeng Chen Yuping Chen Yuxing Xia Yingli Chen 《Optics & Laser Technology》2003,35(3):187-190
We experimentally demonstrate multi-channel wavelength conversion through the cascaded second-order nonlinear processes in periodically poled lithium niobate waveguide in the optical communication wavelength band of 1.5 μm. The normalized conversion efficiency as high as 90% W−1 cm−2 is obtained. Wavelength conversion over a broad wavelength range of 66 nm has been confirmed. 相似文献
2.
Focused ion beam implantation of gallium and dysprosium was used to locally insulate the near-surface two-dimensional electron gas of AlxGa1−xN/GaN heterostructures. The threshold dose for insulation was determined to be 2×1010 cm−1 for 90 keV Ga+ and 1×109 cm−1 for 200 keV Dy2+ at 4.2 K. This offers a tool not only for inter-device insulation but also for direct device fabrication. Making use of “open-T” like insulating line patterns, in-plane gate transistors have been fabricated by focused ion beam implantation. An exemplar with a geometrical channel width of 1.5 μm shows a conductance of 32 μS at 0 V gate voltage and a transconductance of around 4 μS, which is only slightly dependent on the gate voltage. 相似文献
3.
Jinna Li Ming Luo Wenjian Weng Kui Cheng Piyi Du Ge Shen Gaorong Han 《Applied Surface Science》2009,256(1):342-345
Uniformly distributed PbTiO3 nanodots were successfully prepared by phase separation approach. A precursor sol film was first spin-coated on Si wafer and then spontaneously separated into two distinct phases owing to the Marangoni instability. PT nanodots with tailorable size and density were obtained after further heat treatment. X-ray diffraction analysis indicated that these nanodots showed a perovskite structure. An excellent room temperature field emission property of PbTiO3 nanodots was observed: the minimum turn-on voltage was about 5.3 V/μm; while the emission current density reached about 270 μA cm−2 at an applied field of about 9.25 V/μm. 相似文献
4.
Ya. V. Terent'ev V. A. Kaygorodov V. A. Solov'ev B. Ya. Mel'tser A. N. Semenov O. G. Lublinskaya S. V. Sorokin I. V. Sedova S. V. Ivanov P. S. Kop'ev 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):475
We report on the development of a novel design of a mid-IR laser combining III–V and II–VI compounds in a “hybrid” double heterostructure. It possesses large (1.5 eV) potential barriers both for injected electrons and holes, suppressing their leakage from the active region, and provides strong optical confinement. An AlGaAsSb/InAs/CdMgSe laser diode with a III–V/II–VI heterovalent interface at the 0.6 μm-InAs active region has been grown by molecular beam epitaxy on an InAs substrate. Despite a far from optimal defect density at the CdMgSe/InAs interface and high losses inherent for bulk active region of the laser, the structure demonstrates lasing at 2.8 μm (up to 100 K) in the pulsed regime with a threshold current density of 3–4 kA/cm2. Type II InSb monolayer insertions into an InAs layer show bright photoluminescence at 3.8 μm (77 K), confirming the great potential of the InAs-based nanostructure active region for longer wavelength applications. 相似文献
5.
Parameter optimization and characteristic analysis of a polymer microring resonant wavelength multiplexer 总被引:4,自引:0,他引:4
Xian-Yin Wang Chun-Sheng Ma Shu-Lin E Xin Yan Yuan-Zhe Xu Hai-Ming Zhang Da-Ming Zhang Zhan-Chen Cui De-Gui Sun 《Optics & Laser Technology》2005,37(4):337-344
Novel formulas of transmission functions are presented, some parameters are optimized, and transmission characteristics are analyzed for a polymer microring resonant wavelength multiplexer around the central wavelength of 1.55 μm with the wavelength spacing of 5.6 nm and with eight vertical output channels. The computed results show that the designed device possesses some excellent features including the 3 dB bandwidth of 0.25 μm, weaker background light of 3.8×10−4, smaller inserted loss of less than 0.6 dB, and lower crosstalk below −20 dB for every vertical output channel. 相似文献
6.
A report on GaN based metal insulator semiconductor (MIS) ultraviolet (UV) photodetectors (PDs) with atomic layer deposited (ALD) 5-nm-thick HfO2 insulating layer is presented. Very low dark current of 2.24 × 10−11 A and increased photo to dark current contrast ratio was achieved at 10 V. It was found that the dark current was drastically reduced by seven orders of magnitude at 10 V compared to samples without HfO2 insulating layer. The observed decrease in dark current is attributed to the large barrier height which is due to introduction of HfO2 insulating layer and the calculated barrier height was obtained as 0.95 eV. The peak responsivity of HfO2 inserted device was 0.44 mA/W at bias voltage of 15 V. 相似文献
7.
Jung Yong Kim In Jae Chung Changhee Lee Young Chul Kim Jai Kyeong Kim Jae-Woong Yu 《Current Applied Physics》2005,5(6):615-618
N,N′-diphenylbutyl-3,4,9,10-perylenebiscarboximide (PTCDI-C4Ph) were characterized by optical and electrochemical methods. A device with an ITO/PTCDI-C4Ph (≈2 μm)/Al structure was fabricated to measure mobility by time-of-flight techniques. This vacuum deposited organic layer was an amorphous state. Electrons were observed faster than holes. The electron and hole mobilities were 1.8 × 10−4 cm2/V s and 1.1 × 10−4 cm2/V s under the electric field of 500 (V/cm)1/2, respectively. This result shows that this organic compound is a good candidate for an n-type conduction. 相似文献
8.
Yiqiao Chen Aaron Moy Shangheng Xin Kan Mi Peter P. Chow 《Infrared Physics & Technology》2009,52(6):340-343
The effects of atomic hydrogen and polyimide passivation on R0A product of type-II InAs/GaSb superlattice photo detectors for cut-off wavelength of both 6.5 μm and 12 μm were investigated. Low temperature current–voltage measurement shows that the use of atomic hydrogen during molecular beam epitaxy growth can improve R0A product by 260% for 6.5 μm cut-off superlattice diodes and by 50% for 12 μm cut-off ones. The R0A product of polyimide-passivated diodes with 12 μm cut-off is about 80% higher than those un-passivated ones. Wannier–Stark oscillations at higher reverse bias were observed for polyimide-passivated superlattice diodes with 12 μm cut-off. No Wannier–Stark oscillations were observed for un-passivated superlattice diodes, indicating that surface leakage current dominates in un-passivated diodes, while intrinsic dark current mechanisms such as tunneling and diffusion current dominate in polyimide-passivated diodes. 相似文献
9.
The effect of hydrogen (H2) gas exposure on the field emission properties of tin oxide (SnO2) nanowires films synthesized by the carbon thermal reduction vapor transport method was investigated. The exposure of H2 gas results in the reduction of the turn-on voltage for driving a current of 10 nA from 7.6 V/μm to 5.5 V/μm and the increase of the field current based on 10 V/μm from 0.47 μA to 2.1 μA. The Fowler–Nordheim plot obtained from the current–voltage data supports that the field emission enhancement of SNW film is attributed to the reduction of the work function by the H2 exposure. 相似文献
10.
High-speed, oxide-confined, polyimide-planarized 850 nm vertical-cavity surface-emitting lasers (VCSELs) with oxide aperture diameters of 9, 10, 12, 15, 20, and 30 μm have been fabricated and characterized. For a 9 μm oxide aperture diameter, the lasers exhibit a resonance frequency, a 3-dB modulation frequency, and a modulation current efficiency factor (MCEF) up to 12.4, 16.5 GHz, and 10.9 GHz/mA1/2, respectively, at only 7.9 kA/cm2. Threshold voltage and current were 1.45 V and 0.7 mA, respectively. It is demonstrated that increasing the resonance frequency with bias does not guarantee a higher modulation bandwidth. The influence of oxide aperture scaling effect on VCSEL performance is presented. 相似文献
11.
F. Song L. Zhang L. Zhu J. Ge G. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):255-257
The atomic deposited BN films with the thickness of nanometers (ABN) were
prepared by radio frequency magnetron sputtering method and the
nanostructured BN films (CBN) were prepared by Low Energy Cluster Beam
Deposition. UV-Vis Absorption measurement proves the band gap of 4.27 eV and
field emission of the BN films were carried out. F-N plots of all the
samples give a good fitting and demonstrate the F-N tunneling of the
emission process. The emission of ABN begins at the electric field of 14.6 V/μm while that of CBN starts at 5.10 V/μm. Emission current
density of 1 mA/cm2 for ABN needs the field of 20 V/μm while that of
CBN needs only 12.1 V/μm. The cluster-deposited BN on n-type Silicon
substrate proves a good performance in terms of the lower gauge voltage,
more emission sites and higher electron intensity and seems a promising
substitute for the cascade of field emission. 相似文献
12.
Eye-protection glasses against YAG laser injury based on the band gap reflection of one-dimensional photonic crystal 总被引:3,自引:0,他引:3
Ming Chen Chunfei Li Mai Xu Weibiao Wang Shaojie Ma Yuxue Xia 《Optics & Laser Technology》2007,39(1):214-218
Eye-protection glasses against YAG laser injury based on band gap reflection of one-dimensional photonic crystal (PC) is designed and manufactured in this paper. The laser beam (wavelength 1.06 μm) is reflected by the one-dimensional PC (with the transmission 10−7) and absorbed by the phosphatic glass substrate (with the transmission 1% for 1.06 μm), so the transmission of the device for wavelengths of1.06 μm can reach 10−9. The glasses have enough capabilities to protect the eyes from injury of ns-YAG lasers whose energy density is 1 J/cm2 for all incident angles, and also to avoid a second injury to others from the reflected laser beams. The transmission of the glasses is beyond 70% for the visible lights. The testing data of the eye-protection glasses agree well with the theoretical predictions. 相似文献
13.
L. Doyennette A. Vardi F. Guillot L. Nevou M. Tchernycheva A. Lupu R. Colombelli G. Bahir E. Monroy F.H. Julien 《Superlattices and Microstructures》2006,40(4-6):262
We have demonstrated GaN/AlN quantum dots (QD) photodetectors, relying on intraband absorption and in-plane carrier transport in the wetting layer. The devices operate at room temperature in the wavelength range 1.3–1.5 μm. Samples with 20 periods of Si-doped GaN QD layers, separated by 3 nm-thick AlN barriers, have been grown by plasma-assisted molecular-beam epitaxy on an AlN buffer on a c-sapphire substrate. Self-organized dots are formed by the deposition of 5 monolayers of GaN under nitrogen-rich conditions. The dot height is 1.2±0.6 to 1.3±0.6 nm and the dot density is in the range 1011–1012 cm−2. Two ohmic contacts were deposited on the sample surface and annealed in order to contact the buried QD layers. The dots exhibit TM polarized absorption linked to the s–pz transition. The photocurrent at 300 K is slightly blue-shifted with respect to the s–pz intraband absorption. The responsivity increases exponentially with temperature and reaches a record value of 10 mA/W at 300 K for detectors with interdigitated contacts. 相似文献
14.
In this paper the results of DC-conductivity investigation of 1,4-cis-polybutadiene thin films doped with 5% weight of silicon carbonate (SiC) of nanocrystalline form with the size of grains being about 20 nm are presented. The aim of the study was to receive a knowledge about the electrical properties and DC-conductivity mechanisms depending on film thickness, temperature and electric field magnitude. The investigated films thickness ranged from 1 to 12 μm. The investigations were carried out for both undoped and doped with nanocrystalline SiC polymers. The current flow through the material bulk changed from 10−12 to 10−4 A with applied electric fields of 0 to 3 × 107 V/m and temperature of the film varying from 15 to 325 K. It was observed that the magnitude of the current flow through the investigated material bulk is governed by a phase state of the polymer and the presence of SiC in the bulk. The charge transport through the material bulk is controlled by the Poole-Frenkel phenomenon as well as by hopping. The determined activation energies were between kT and 0.36 eV. 相似文献
15.
Huiying Fu Huanrong Wu Xiaoyuan Hou Fei Xiao Bingxian Shao 《Current Applied Physics》2007,7(6):697-701
The donor–acceptor functionalized molecule, bis(4-(2-(3,3-dicyanomethylene-5,5-dimethyl-1-cyclohexylidene)vinyl)phenyl)(1-naphthyl)amine (DPN-4CN), with symmetrical structure, was investigated for its application in optoelectronic devices. Red organic light-emitting diodes (OLEDs) were fabricated by doping DPN-4CN in tris(8-hydroxyquinolino) aluminum (Alq3) as red emitters, with a structure of ITO/NPB/Alq3:DPN-4CN/BCP/Alq3/LiF/Al. The device with a doping concentration of 2.5 wt% showed pure red emission with λmax at 654 nm and CIE coordinates of (0.62, 0.36), a high brightness of 5080 cd m−2 at a driving voltage of 12 V, a current efficiency of 2.14 cd A−1 and an external quantum efficiency of 1.07% at a current density of 20 mA cm−2. The current efficiencies and CIE coordinates of the device were almost constant over a current density from 1 to 200 mA cm−2. 相似文献
16.
Mohd. Yusri Abd. Rahman Muhamad Mat Salleh Ibrahim Abu Talib Muhamad Yahaya 《Current Applied Physics》2005,5(6):599-602
This paper reports the effect of surface topography of titanium dioxide films on short-circuit current density of photoelectrochemical solar cell of ITO/TiO2/PVC-LiCLO4/graphite. The films were deposited onto ITO-covered glass substrate by screen-printing technique. The films were tempered at 300 °C, 350 °C, 400 °C, 450 °C and 500 °C for 30 min to burn out the organic parts and to achieve the films with porous structure. The surface roughness of the films were studied using scanning electron microscope (SEM). Current–voltage relationship of the devices were characterized in dark at room temperature and under illumination of 100 mW cm−2 light from tungsten halogen lamp at 50 °C. The device utilising the TiO2 film annealed at 400 °C produces the highest short-circuit current density and open-circuit voltage as it posses the smoothest surface topography with the electrolyte. The short-circuit current density and open-circuit voltage of the devices increase with the decreasing grain size of the TiO2 films. The short-circuit current density and open-circuit voltage are 0.6 μA/cm2 and 109 mV respectively. 相似文献
17.
Fast electro-optical switching and high contrast ratio in epoxy-based polymer dispersed liquid crystals 总被引:1,自引:0,他引:1
We report the observation of an electro-optical switching effect from an opaque to a transparent state occurring at a threshold value of the applied field in a polymer dispersed liquid crystal (PDLC). Optical responses of the composite film under the conditions of an externally applied ac electric field (2–5 Vp−p/μ) and a film thickness (50 μm), were determined using an Argon laser (wavelength 514 nm). The experimental results showed promising switching times with a rise time of 190 μs and a decay time of 2 ms and an exceptionally high contrast ratio up to 410. These results demonstrate the validity of employing this new PDLC in electro-optical devices. 相似文献
18.
A. I. Yakimov A. V. Dvurechenskii V. V. Kirienko A. I. Nikiforov 《Physics of the Solid State》2005,47(1):34-37
Photodetectors based on Ge/Si multilayer heterostructures with germanium quantum dots are fabricated for use in fiber-optic communication lines operating in the wavelength range 1.30–1.55 μm. These photodetectors can be embedded in an array of photonic circuit elements on a single silicon chip. The sheet density of germanium quantum dots falls in the range from 0.3 × 1012 to 1.0 × 1012 cm?2, and their lateral size is approximately equal to 10 nm. The heterostructures are grown by molecular-beam epitaxy. For a reverse bias of 1 V, the dark current density reaches 2 × 10?5 A/cm2. This value is the lowest in the data on dark current densities available in the literature for Ge/Si photodetectors at room temperature. The quantum efficiency of photodiodes and phototransistors subjected to illumination from the side of the plane of the p-n junctions is found to be 3% at a wavelength of 1.3 μm. It is demonstrated that the maximum quantum efficiency is achieved for edge-illuminated waveguide structures and can be as high as 21 and 16% at wavelengths of 1.3 and 1.5 μm, respectively. 相似文献
19.
O. A. Mironov M. Myronov S. Durov V. T. Igumenov V. M. Konstantinov V. V. Paramonov T. Zhang L. F. Cohen 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):523
Magnetotransport at fields up to 500 mT and LF-noise characteristics are reported for miniature magnetoresistors with ferrite concentrators based on Sn-doped n-InSb/i-GaAs heterostructures grown by MBE. The thickness of the InSb epilayers lie in the range 0.55–1.5 μm giving room temperature mobilities of 2.5–5.5 m2 V−1 s−1 with carrier densities of (0.5–1.5)×1017 cm−3. The room temperature magnetoresistance (MR) for our two terminal devices could be as high as 115% at 50 mT which is comparable to the extraordinary MR (ExMR) recently reported in microscopic composite van der Pauw disks four terminal devices [Science 289 (2000) 1530]. In addition, a high signal-to-noise ratio and a good temperature stability of R(B)/R0=0.5–0.83% K−1 was observed for B<60 mT (below the saturation field Bsat for ferrite). Device resistance stability R0(T) was equal to 0.27–0.66% K−1 in zero field with a nominal device resistance R0=197–224 Ω for DC currents in the range I=0.01–1.0 mA. The minimum detectable magnetic field is estimated from the reduced differential MR (∂R/∂B)/R=2000% T−1 at B=31 mT and normalised 1/f current noise power spectral density measured at the same field. The resolution limit Bmin=2.6 nT at 102 Hz and Bmin=0.82 nT at 103 Hz. These resolution limits are seven times better than those recently reported for the same material n-InSb/i-GaAs and ferrite fabricated Hall sensors [Magnetotransport and Raman characterization of n-InSb/i-GaAs epilayers, for Hall sensors applications over extremely wide ranges of temperature and magnetic field, Proceedings NGS 10, IPAP Conference Series 2, IPAP, Tokyo, 2001, pp. 151–154]. 相似文献
20.
J. R. Lindle W. W. Bewley I. Vurgaftman J. R. Meyer J. L. Johnson M. L. Thomas W. E. Tennant 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):558
A self-referencing, optical modulation technique was used to measure the negative luminescence efficiencies of an array of mid-wave infrared HgCdTe photodiodes with cutoff wavelength 4.6 μm as a function of sample temperature. The internal efficiency at a wavelength of 4 μm was 93% at 295 K, and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction >50 K at room temperature and >30 K at 240 K. Moreover, the reverse-bias saturation current density was only 0.13 A/cm2. The measured transmission and emission spectra were simulated using empirical HgCdTe absorption formulas from the literature. 相似文献