Low Level Light (LLL) night vision technology is extensively applied in national defense and civil application fields. The digitization of LLL imaging is trend of light detection technology in the future. The corresponding modulation transfer function (MTF) and total system MTF model were established, base on the structure composition and operation principle. Simulation was carried out to analyze the performance of the MTF modern. Results indicate that the MCPCMOS better contrast of object. When the spatial frequency increasing, the MTF of MCP-CMOS downing faster than that of GaAs LLL image intensifier. The GaAs image intensifier shows an better image restoration capability and higher limiting resolution. The model and simulation results can provide a theoretical guidance for the fabrication and application of high imaging quality MCP-CMOS.
Using the projected augmented wave potential by the density functional theory based upon gradual gradient approach method and the slab model, from the calculated surface, we identify the relaxed atoms sites of GaAs(110) surface, the electronic structure of elements K and O adsorpted on binding sites of ideal GaAs(110) surface have also been calculated, especially the total energy of the adsorption system. The comparison results of calculated total energy showed: for K and O elements at highest coverage of Θ=1ML on GaAs(110) surface, they were not formed to local domain of competitive chemical adsorption, while they were formed to a compound uniformity phase of cooperative chemical adsorption. Our calculated results providing theoretical basis and reference for the application of alkali oxidation adsorpted on GaAs surface to form a negative electron affinity photocathode.
As an III-V semiconductor material, InxGa1-xAs can response from 0.87μm (GaAs) to 3.5μm (InAs) by tuning the relative amount of Gallium in the alloy. In order to get better the response of the photocathode in near infrared
radiation region (1~1.7μm), InGaAs/InP heterostructure is widely used for photocathode material. The only
composition of In0.53Ga0.47As is lattice matched to the InP substrate and their spectral response is from 0.9μm to 1.6μm. thus In0.53Ga0.47As/InP heterostructure is selected for near infrared response photocathode. The In0.53Ga0.47As layer has been grown on InP substrate used for photocathode by solid source molecular beam epitaxiy (SS-MBE). The photocathode samples were grown to optimize the growth temperature, III/V ratio and growth rate. The In0.53Ga0.47As layer crystalline quality and component were performed by applying high resolution X-ray diffractometer, surface roughness investigations were performed by applying atomic force microscopy. The
Be doping characteristic was checked by the electrochemical capacitance-voltage（ECV）. The optical performance of the photocathode is measured by the spectral meter. The collected information is being used to correct and enhance growth characteristics and optimize InGaAs/InP photocathode structure to increase spectral response and quantum efficiency.
The ideal status of the GaAs photocathode bonding assembly is as fellows: the GaAs photocathode should
not have additional stress; the crystal lattice should keep integrity after deposited Si3N4 reflection reducing
coating and bonging process that GaAs epitaxial material on a glass window. In order to estimating the
bonding quality of the GaAs photocathode bonding assembly, integral photoluminescence intensity was
calculated on the ideal bonding condition. Assuming the energy of incident light was absorbed by GaAs
active layer except reflection, according to the optical character of the GaAs photocathode bonding
assembly, the value was calculated. This value could be the standard to assess the quality of the GaAs
photocathode bonding assembly and improve the bonding technology that the GaAs epitaxial material is
bonded to a glass window.
This paper investigates date retention ability of EEPROM cells for a given voltage or temperature by theory and
experiment. The expression of EEPROM date retention is derived. In the temperature acceleration experiment, the
logarithm of device inactivation time have linear ratio with temperature according to Arrhenius formula and the device
life retention was acquired in the various temperature. According to Arrhenius equation, lifetime curve is deduced. In the
electric acceleration experiment, because of the charge leaking on the floating-gate, the threshold voltage would decrease
gradually. In the log-log plot, the decrease efficiency of threshold voltage have linear ratio with time. Under the
assumption that the charge loss mechanism is Fowler-Nordheim tunneling through the thin oxide, date retention time of
EEPROM cells is derived and the experience formula is derived by experiment.
The GaAs photocathode has been widely used in optoelectronic devices such as image intensifiers and
photomultiplier tubes, but it is inevitable for these devices to withstand a variety of mechanical shock. In order to study
the impact on the GaAs photocathode’s photoemission performance caused by mechanical shock, GaAs photocathode
image intensifier is researched in this paper . The spectral response of the GaAs photocathode was tested respectively
before and after several value of mechanical shock（the value of mechanical shock:55g，65g，75g，85g and 95g）.The
parameter of the GaAs photocathode can be calculated and the quantum efficiency curve can be fitted as well using the
MATLAB software. The results show that surface escape probability is increased after photocathode is subjected to
mechanical shock, so that its photoemission performance will be improved. We think this phenomenon is due to the
GaAs photocathode surface Cs-O reconstruction. This finding provided a new method to enhance the photoemission
performance of photocathode.
The simulation calculation and analysis on the electron transmittance and ion stopping power for ion barrier films (IBFs)
of BN were performed by Monte Carlo methods. The interaction model between particles and solids were described. We
find the Dead Voltage of BN IBFs is 220V. When the energy of the incident ions is 0.2~0.3KeV, 91%—99% of C+, N+ and O+ are stopped by BN IBFs; while 12%—19% of H+ for BN IBF. The results indicate that BN is an idea candidate for ion barrier films. This work provided a theory support for fabricating high performance low-level-light device.
The simulation calculation and analysis of electron back-scattering characteristics for ion barrier films (IBFs) of Al2O3
was performed by Monte Carlo methods. A physical model for the interaction of low-energy electrons with solid was
described. Trajectory and spatial distribution of the electrons were simulated with MATLAB software.The maximum
ratio of the back-scattered electrons was 19% at the incident energy of 0.24 keV. Beyond this value, the number of backscattered
electron decreased slowly with the increase of the incident energy. The back-scattering ratio increased almost
linearly with the increase of IBF density. When the incident energy was 0.7 keV and the film thickness is higher than 7
nm, the electron back-scattering ratio was always ~17% for the Al2O3 IBF. This work provided a theory support for
fabricating high performance low-level-light device.
A comparative study of semi-insulating GaAs substrate, p-AlxGa1-x As/ semi-insulating GaAs and p-GaAs/p-AlxGa1-xAs/ semi-insulating GaAs structure has been done using the surface photovoltage (SPV) spectroscopy in metal–insulator–semiconductor (MIS) configuration. Which space charge region (SCR) dominated contribution to SPV in a certain wavelength range was determined. The SPV signals were calculated in a similar way as the open circuit voltage of an illuminated photodiode. One-dimensional continuity equations was adopted for determine the distribution of excess
minority carrier. The ideality factor of MIS configuration was investigated in air ambient. The contributions for SPV
signal of different layers were discussed in detail. At last the minority carrier diffusion length of different layers and
surface or interface recombination velocity were simulated.
There has been extensive applcations in the area of photoelectronic device because InGaAs grown on the GaAs substrate have advantageous photoelectronic performance and adjustable band gap. The main obstacle to acquiring high crystalline quality of InGaAs grown on GaAs substrate comes from the large lattice mismatch between InGaAs overlayer and GaAs substrate. It is particularly detrimental to the structure and photoelectronic property of InGaAs thin films that lager roughness of surface and high misfit dislocation density is introduced because of the defect onset during the growth. The In0.1Ga0.9As layers with and without linearly graded buffer layers grown on GaAs substrate had been studied. The investigations were performed by applying atomic force microscopy (AFM), high resolution X-ray diffractometry (HR
XRD). A linearly graded buffer layer is effective for lowering the misfit dislocation density in In0.1Ga0.9As layers on a GaAs substrate, but it can not end the dislocation in buffer layer completely. All above-mentioned is also confirmed in HRXRD results.
We report growth of high Aluminum content and heavy P type doping AlGaAs by molecular beam epitaxy (MBE) for
extended blue photocathode window layer. The key factors which affect of extended blue photocathode window AlGaAs
layer during epitaxy growth were analyzed and show that growth conditions such as V/III flux ratio, substrate
temperature and growth rate have dramatically effected on the AlGaAs layer crystalline quality and morphology. On the
basis of the optimized V/III flux ratio and appropriate growth rate, the substrate temperature for sample growth was
adjusted, the P type heavy doping(≥5×1018cm-3) and large area AlGaAs single crystal material with excellent crystalline
quality and good luminescence properties was fabricated on GaAs (100) substrate. The morphology of the samples was
checked by high resolution optical microscopy. The crystalline quality of samples was measured by X-ray diffraction and
luminescence property was measured by integral luminescence system. The relationship of the crystalline quality and
substrate temperature was got. The excellent crystalline quality AlGaAs layer obtained have been applied to GENIII
photocathode windows layer and spectral response range of photocathode extended to blue-green light in short wave.
The Quantum efficiency in the blue-green wave range of GENIII photocathode is enhanced.