KEYWORDS: Information technology, Internet, Photonics, Mechanics, Education and training, Defense and security, Social sciences, Polishing, Satellites, Analytical research
The proposed concept concerns master students education based on implementing projects. The total educational structure has feedback from students and professors and is based on using theory of automatic operation related to the education process.
Modern technology advances combined with unique physical properties of mercury cadmium telluride (MCT)
material, empower low-signal applications in technical vision systems. Properties of MCT detectors manufactured from
LPE and MBE epilayers and their dependences on thickness and doping both for IR and THz regions are discussed. It is
shown by comparison of experimental data and modeling of I-V dark current characteristics that MCT photodiode
ultimate electrical characteristics are limited by diffusion current in n+-n--p junctions and by current via the deep traps
in the gap with position Et= 0.7 Eg above the valence band and concentrations Nt = (1.0-5.5)•1015 cm-3 which are
comparable with donor concentration in n--region Nd = (1.1-1.8)•1015 cm-3. Detector array parameters for a wavelength
range 8-12 microns are: detectivity D*=1.9•1011 cm•Hz1/2/W, noise equivalent difference temperature NEDT ≈ 9 mK,
dynamical resistance R ≈ 4·109 Ohm for the reverse biases ΔV = 0.1-0.2 V.
Also, it is shown that MCT layers can be successfully used as sub-mm or mm wave ambient temperature or
moderately cooled hot electron bolometers. Thus, in addition to the wavelength range from SWIR to VLIR, where the
MCT detectors are employed mainly as photodiodes or photoresistors, they can be used as sub-mm or mm wave
detectors in the range from 190 microns to 8 mm. They can be employed here as semiconductor hot electron bolometers
(SHEB). Measurements performed at electromagnetic wave frequencies ν = 37, 55, 77 GHz, and also at 0.89 and 1.58
THz with non-optimized Hg0.8Cd0.2Te bolometer prototype, has confirmed the basic concepts of SHEB. At ν = 0.89
THz, 77 GHz and 37 GHz the signal temperature dependencies were measured too. At 77 K the SHEB sensitivity at ν =
37 and 77 GHz is increasing up to two orders compared to room temperature data. The sensitivity Sν ≈ 2 V/W at 300 K,
and calculated both Johnson-Nyquist and generation-recombination noise values give estimations of SHEB NEP ~ 4•10-10
W at band-width Δf = 1 Hz and ν = 37 GHz.
The modern systems of vision in infrared spectrum (IR) require elaboration of large-area nondefective imaging area with
small pitch (less 40 μm) IR FPA. One of the directions is fabrication hybrid FPA, consisting of several of arrays of
photodiodes based on MCT films (HgxCd1-xTe on GaAs substrates) and readout circuits on silicon. Substitution of
photodiodes array of large-area imaging area on few arrays of smaller image size, allows having the imaging area of the
required size without fault pixels. The main requirement is the permanent period of photodetectors on component imaging
areas. without loss of pixels on lines of gaps of the butting between arrays. Using concentrated laser radiation, for scribing
the surfaces MCT film on GaAs substrate, under concrete conditions, allows to realize offered above direction. The
determination of the border of zone of the influence of the laser radiation on electric characteristic of p-n junction of the
MCT films and technological ways of the reduction of area of influence of the laser radiation are presented in work.
We had studied the change of parameters of photodiodes on base MCT films depending on distances before laser dicing
grooves and condition of the laser radiation.
As source of the laser radiation we used pulsed UV laser (LGI-21) at 0,34 μm wavelength with pulse duration 7 ns,
frequency of repetition 50 - 100 Hz and power in pulse 2 KW.
We founded condition of the laser dicing on distances 18 - 20 μm from photodiodes, when initial current-voltage
characteristics of photodiodes are saved.
We designed method of the laser dicing of linear photodiodes on MCT films, and we used it to create of multichips hybrid
IR FPA. The result is non damage dicing of linear photodiodes on MCT films (λc =12 μm) on distances 18 - 20 μm from p-n
junctions.
The measurement signal (S) to noise (N) ratio (S/N) of novel 128×128 FPA in temperature range 77 -130K was carried
out. FPA for spectral range 8-12 μm was fabricated by B+ implantation process into graded MCT P-p heterojunction with potential barrier. MCT P-p heterojunction with specific MCT composition throughout the thickness was grown by MBE
on GaAs substrate by ellipsometric control in situ. The potential barrier was determined by the difference of MCT
composition at absorber and p-n junction location layers and equal to ΔXCdTe = 0,025. It was shown that based on P-p
heterojunction FPA operated temperature and wavelength increases over routine one without P-p heterojunction.
Keywords: graded gap layers, heterojunction, MCT, photodiodes, FPA.
Comparative analysis of four 4x288 different designed readouts elaborated at the Institute of Microdevices and the Institute of Semiconductor Physics is presented. Also some features of design 576x6 readouts adduced. All the readouts have the direct injection input circuit with incorporated cells allowing testing without photodiodes. TDI registers have three delay elements between neighbor inputs. Some characteristics of 4x288 FPAs with mercury-cadmium-telluride TDI arrays are cited too. 2-phase and 4-phase CCD readouts (2.5 micron technology) have different channel types (surface, buried and semi-buried), which include 10 bit TDI registers in each channel, and 18 channel multiplexing to 16 outputs. Two polysili-con, one metal level and 400 A dielectric layers were used. The readouts characteristics: charge handling capacity, transfer characteristics, output nonlinearity characteristics, bias dispersion, etc. are presented. CCD technology used for data multiplication results in crosstalk increase, because of the presence of rather considerable transfer inefficiency at cryogenic temperatures. Using 2.5 micron CCD technology and 2.0 CMOS technology the readouts, which include the digital interface for dead pixels deselection, preliminary amplification circuits, 36 channel multiplication by CCD registers and 2 beat multiplication by analogue switches to 4 output amplifiers, were manufactured. One pocket CMOS technology with two polysilicon, two metal levels and 350 A dielectric layers were used. To increase the linearity of transfer characteristics and noise level decrease at the output of CCD the circuits of charge-voltage conversion on the base of operational amplifiers were used. This allows getting circuits with parameters close to those obtained by 0.8 - 1.0 micron CMOS technology. Also some characteristics of 4x288 readouts designed by 1.2 micron CMOS technology are discussed (two polysilicon and two metal levels). This one includes the circuits of auxiliary electronics. Comparative analysis shows that the readouts mentioned are different in numbers of outputs, external service but have rather similar parameters.
Ultimate performance small-pitched infrared focal plane arrays (FPA) are of the great interest for development and production of state-of-the-art special and common use thermal imagers. Novel MBE-grown Hg1-xCdxTe/CdZnTe/GaAs heterostructures (MCT/CZT on GaAs HS) are considered perspective for implementation of sophisticated FPA concepts including multi-color and HOT (high operating temperature). Performance of MWIR and LWIR photoconductive (PC) and photovoltaic (PV) infrared detectors fabricated on the base of a. m. heterostructures are presented. The main feature of developed technology is formation of multi-layer device structure in single MBE growth run with precise control of thickness and alloy composition "x" across individual layers and hence throughout heterostructure. Flexible HS design results in half-finished products of PC and PV detectors with optimized parameters of absorber and perfect interfaces between absorber and blocking layers providing effective suppression of surface recombination and surface leakage currents. Giant peak responsivity RV (λco=10.5 μm, 500 K, 1200 Hz) over 6,0×105 V/W was reached on LWIR PC. Average values D* = 1.8×1011 cmHz1/2W-1 and NEDT = 9 mκ were measured on 4×288 PV FPA with λco = 11.2 μm at T=78 K just as 23 mK and 19 mκ on 320×256(240) PV FPA with λco = 5.5 and λco = 10.2 μm at T=78 K.
The electro-physical and photo-electrical properties of the HgCdTe/SiO2/Si3N4 and HgCdTe/anodic-oxide film MIS structures is experimentally studied. The heteroepitaxial graded-band films Hg0.78Cd0.22Te were produced on the GaAs substrates by molecular-beam epitaxy. It was established of features of electrical properties were related with conduction type of the semiconductor and to the presence of near-surface graded-band layers. The test measurements of the electro-physical and photoelectric performances of MIS-structures in base of graded-band HgCdTe are held and the following parameters are found: resistances of volume, voltage of flat bands, densities of mobile and fixed charges, spectrums of surface states. It is shown that low-temperature double insulator SiO2/Si3N4 is perspective for passivation of surface of focal plane arrays in base of HgCdTe-photodiodes.
CdTe and HgCdTe layers were grown by MBE on GaAs(310) and Si(310) substrates. The dependences of microrelief height and macroscopic defects densities on the growth conditions of CdTe layer are plotted. CdTe buffer layers with the average height of surface relief of 2 nm are obtained. HgCdTe layers on GaAs(310) substrates with V-shaped defects density of 200-300 cm-2 were grown. When Si(310) substrates are used, the boundaries between antiphase domains are an additional reason for formation of V-shaped defects. It is shown, that the optimization of surface preparation processes and the growth conditions allows to grow one-domain films of CdTe buffer layers on Si(310) substrates and to lower the density of V-shaped defects.
The mathematical model, algorithm and calculation results of a convection current in the channel of a microchannel plate represented in view of reaction channel to entrance current. Methods of the theory of electric circuits are used. Calculation in static and in transition modes is possible. The model allows to install interrelation between the mode of an amplification and parameters of the resistive and emissive MCP layers.
Properties of n+-on-p HgCdTe photodiode with graded p-P heterojunction at temperature 77 K are analysed numerically by solving three-dimensional diffusion equation in cylindrical geometry. Dependences of photodiode's parameters from composition difference Δx and position of p-n junction in relation to heterojunction are presented. Elimination of lateral collection of diffusion current with increasing of Δx is shown.
4×288 MCT LWIR linear arrays with 28X25 μm diodes and silicon ROICs were designed, manufactured and tested. MCT layers were grown by MBE technology on (013) GaAs substrates with CdTe/ZnTe buffer layers and λco = 11.2±0.15 μm at T = 78 K. CCD and CMOS “hybrid” technology for design and manufacture of silicon ROICs was used. The design rules 2.5 μm for CCD technology and 2.0 μm design rules for CMOS technology happened to be sufficient to realize most of the functions for 288×4 MCT TDI array. Analog functions were realized by CCD elements. An amplification of the output signals is realized by CMOS buffer amplifier. Decoding and deselection code storing functions are accomplished by digital CMOS elements. 288 information channels were attached to 4 analog outputs operating in the frequency range f≤4 MHz clock. Total consumption power measured is 50 mW at T = 298 K and 70 mW at T = 78 K. Before hybridization the parameters of MCT linear arrays and Si readouts were tested separately. With aperture 280×640 the detectivities Dλ ≈ 1.8.1011 cm.Hz1/2/W were achieved (λco ≈ 11.2 μm, λmax 10.0 μm) with standard deviation about 15 % and operability close to 100 %.
MCT 2×64 and 4×288 linear arrays with silicon readouts were designed, manufactured and tested. (013) MCT MBE layers were grown on GaAs substrates with ZnTe and CdTe buffer layers. 2×64 arrays were also manufactured on the base of LPE layers on CdZnTe (111) substrates. 50×55 and ≈30×30 μm area n-p-type photodiodes were formed by 50 ÷ 120 keV boron implantation. The dark currents at V ≈ 100 mV reversed biased diodes used in arrays with cutoff wavelength λco ≈ 10.0 - 12.2 μm were within 15 - 50 nA and zero bias resistance-area products were within R0A ≈ 5 ÷ 20 Ohm×cm2. Designed silicon readouts with skimming and partitioning functions were manufactured by n-channel MOS technology with buried or surface channel CCD register. For achievement with the silicon readouts the deselection function, the “composite” technology approach was considered. In this case both the technology of n-channel CCD and CMOS technology were applied, which allow to weaken considerably the technological design rules for realization of 288×4 readouts with deselection of “dead” elements. It is shown that 2.5 μm design rules for CCD and 2.0 design rules for CMOS technologies allow to realize most of the functions needed for 288×4 MCT array operation with deselection function. Before hybridisation the parameters of MCT linear arrays and Si readouts were tested separately. HgCdTe arrays and Si readouts were hybridised by cold welding In bumps technology. In dependence of FOV with skimming mode used for integration time of 8 - 20 μs detectivities within D*λ (0.4 - 1.7)×1011 cm×Hz1/2/W were achieved in dependence of the array format. Dark carrier transport mechanisms in MCT diodes were calculated and compared with experimental data.
View of basic and specific physical and chemical features of growth and defect formation in mercury cadmium telluride (MCT) heterostructures (HS's) on GaAs substrates by molecular beam epitaxy (MBE) was made. On the basis of this knowledge a new generation of ultra high vacuum set, ultra-fast ellipsometer of high accuracy and automatic system for control of technological processes was produced for reproducibility of MCT Hs's growth on substrates up to 4" in diameter. The development of industrially oriented technolgoy of MCT HS's growth by MBE on GaAs substrates 2" in diameter and without intentional doping is presented. The electrical characteristics of n-type and p-type of MCT HS's and uniformity of MCT composition over the surface area are excellent. The residual donor and acceptor centres are supposed as hypothetically tellurium atoms in metallic sublattice ("antisite" tellurium) and double-ionised mercury vacancies. The technology of fabricating focal plane arrays is developed. The high quality characteristics of infrared detectors conductance and diode mode are measured. Calculations of detector parameters predicted the improvement in serial resistance and detectivity of infrared diode detectors based on MCT heterostructures with graded composition throughout the thickness.
x4×288 heteroepitaxial mercury-cadmium telluride (MCT) linear arrays for long wavelength infrared (LWIR) applications with 28×25 micron diodes and charge coupled devices (CCD) silicon readouts were designed, manufactured and tested. MCT heteroepitaxial layers were grown by MBE technology on (013) GaAs substrates with CdZnTe buffer layers and have cutoff wavelength λco ≈ 11.8 μm at T = 78 K. To decrease the surface influence of the carriers recombination processes the layers with composition changes and its increase both toward the surface and HgCdTe/CdZnTe boundary were grown. Silicon read-outs with CCD multiplexers with input direct injection circuits were designed, manufactured and tested. The testing procedure to qualify read-out integrated circuits (ROICs) on wafer level at T = 300 K was worked out. The silicon read-outs for 4×288 arrays, with skimming and partitioning functions included were manufactured by n-channel MOS technology with buried or surface channel CCD register. Designed CCD readouts are driven with four- or two-phase clock pulses. The HgCdTe arrays and Si CCD readouts were hybridized by cold welding indium bumps technology. With skimming mode used for 4×288 MCT n-p-junctions, the detectivity was about (formula available in paper) for background temperature Tb = 295 K.
A complete technological cycle has been designed to produce photodetector arrays, which involves MBE growth of Hg1-xCdxTe (MCT) heteroepitaxial layers, fabrication of MCT-based photodetector structures, manufacture of silicon array multiplexers and hybrid assembly of a photodetector module consisting of a photodetector and multiplexer by means of indium micro bumps. Photoelectric parameters are given of photodetector array modules on the basis of photodiodes for the middle (3 - 3.5 μm) and far (8 - 12 μm) infrared ranges, operating at 78 - 80 K and 200 - 220 K temperatures.
Precise measurements of frequency stability of laser frequency standards require very special instrumentation: precision high-speed digital frequency meter with zero 'dead time'. New hardware and software instrumentation has been designed and successfully tested on highest accuracy laser heterodyne systems. Original methods of measuring and data processing allow estimation of frequency stability with the accuracy of 1 5-th order. This instrumentation was used in measurements of frequency stability of He-Ne/CH4 laser during a period of the time of 0.005s with a resolution better than 1Hz. With hardware based on Pentium-! ! ! the possibility of real-time counting and plotting in several windows frequency vs time, Allen variance vs period and others useful dependences are demonstrated and used. The data throughput with simultaneous real-time renewal of statistics is 1000 samples per second.
A technology was designed and the photodetector modules were manufactured for the 3 - 5 and 8 - 12 μm spectral range based on the Hg1-xCdxTe/GaAs heterostructures and GaAs/AlGaAs multiquantum well structures grown by the molecular beam epitaxy method. The photosensitive HgCdTe layers were grown on the GaAs substrates with the intermediate buffer layer of CdZnTe. To decrease the surface influence on the recombination processes graded gap HgCdTe layers with the increased to the surface composition were grown. A silicon multiplexer was designed and manufactured on the CMOS/CCD technology with frame rate 50 Hz. Hybrid assembly of the photodetectors array and the multiplexer was produced by the group cold welding on the indium bumps with control of the connection process. The manufactured 128 X 128 FPAs on the HgCdTe with the cut-off wavelength 6 μm and 8.7 μm had the NEDT value 0.02 K and 0.032 K, correspondingly, at operating temperature 78 K and frame rate 50 Hz. The photosensitive GaAs/AlGaAs multiquantum well structures were manufactured by the MBE method. It is shown that the designed technology allows to produce 128 X 128 photodetector arrays (λmax = 8 μm) with the NEDT value 0.021 K and 0.06 K at operating temperature 54 K and 65 K, correspondingly.
A technology was designed and the photodetector modules were manufactured for the 3 - 5 and 8 - 12 micrometer spectral range based on the Hg1-xCdxTe/GaAs heterostructures and GaAs/AlGaAs multiquantum well structures grown by the molecular beam epitaxy method. The photosensitive HgCdTe layers were grown on the GaAs substrates with the intermediate buffer layer of CdZnTe. To decrease the surface influence on the recombination processes graded gap HgCdTe layers with the increased to the surface composition were grown. A silicon multiplexer was designed and manufactured on the CMOS/CCD technology with frame rate 50 Hz. Hybrid assembly of the photodetectors array and the multiplexer was produced by the group cold welding on the indium bumps with control of the connection process. The manufactured 128 X 128 FPAs on the HgCdTe with the cut-off wavelength 6 micrometer and 8.7 micrometer had the NEDT value 0.02 K and 0.032 K, correspondingly, at operating temperature 78 K and frame rate 50 Hz. The photosensitive GaAs/AlGaAs multiquantum well structures were manufactured by the MBE method. It is shown that the designed technology allows to produce 128 X 128 photodetector arrays ((lambda) max equals 8 micrometer) with the NEDT value 0.021 K and 0.06 K at operating temperature 54 K and 65 K, correspondingly.
Two X sixty-four linear photodiode arrays on the base of HgCdTe MBE grown layers with CCD silicon readouts were designed, fabricated and tested. It is shown that detectivity for the given arrays even with skimming mode used for long integration times that is need for large square n-p-junctions used and cut-off wavelength of 12.2 micrometer was near the ultimate performance limit.
The molecular beam epitaxy (MBE) set-up with analytical control equipment of growth process was designed and fabricated for growing A2B6 compounds including the mercury-containing ones. A technology was elaborated for growing mercury-cadmium-telluride (MCT) solid solution heteroepitaxial structures (HS) by molecular beam epitaxy (MBE) method with a given variation of MCT composition throughout the thickness. HS's MCT MBE on CdZnTe/GaAs substrate with different variation composition in layers at MCT film interfaces were designing and growing. These structures were used for manufacture of high quality single, linear and array photoconductors (PC) and photodiodes (PD) operating at 77 K and 200 - 250 K temperature in the wavelength range of 3 - 5 micrometer and 8 - 12 micrometer, up and over 20 micrometer. Widegap layers at MCT film interfaces are used as passivating coating. Narrowgap layer at MCT film/CdZnTe buffer layers interface is used for decrease of PD series resistance. For decrease of dark currents of photodiodes array operating at 200 K HS MCT MBE were used with special composition distribution of composition throughout the thickness.
A technology was designed and the photodetector modules were manufactured for the 3-5 and 8-12 micrometers spectral range based on the Hg1-xCdxTe/GaAs heterostructures and GaAs/AlGaAs multiquantum well structures grown by the molecular beam epitaxy method. The photosensitive HgCdTe layers were grown on the GaAs substrates with the intermediate buffer layer of CdZnTe. To decrease the surface influence on the recombination processes graded gap HgCdTe layers with the increase to the surface composition were grown. A silicon multiplexer was designed and manufactured on the CMOS/CCD technology with frame rate 50 Hz. Hybrid assembly of the photodetectors array and the multiplexer was produced by the group cold welding on the indium bumps with control of the connection process. The manufactured 128 x 128 FPAs on the HgCdTe with the cut- off wavelength 6 micrometers and 8.7 micrometers had the NEDT value 0.02 K and 0.032 K, correspondingly, at operating temperature 78K and frame rate 50Hz. The photosensitive GaAs/AlGaAs multiquantum well structures were manufactured by the MBE method. It is shown that the designed technology allows to produce 129 x 128 photodetector arrays ((lambda) max=8 mum) with the NEDT value 0.021 K and 0.06 K at operating temperature of 54 K and 65 K, correspondingly.
For manufacture of focal plane arrays (FPA) the MBE grown heteroepitaxial structures GaAs/CdZnTe/CdHgTe with cut-off wavelength ((lambda) c) of 6.0 and 8.7 micrometers were used. The photosensitive CdHgTe layer was grown with special composition profile in depth being continuously controlled in the growth process. On these structures by the method of low temperature planar technology the 128x128 photodetector arrays were manufactured, including the ones with low series resistance for the far IR range. The read-out circuit was designed and silicon array multiplexers were manufactured CMOS technology with n- pocket. The read-out circuit allows to control the accumulation time at a fixed frame time. The technology of hybrid assembling with continuous control over cold welding on indium bumps was designed and the 128X128 FPAs were fabricated by means of this technology. The noise-equivalent difference of temperature (NEDT) value was 19.7 and 27.2 mK for modules with (lambda) c=6.0 micrometers and 8.7 micrometers correspondingly at the background temperature 77K. Using the IR camera the examples of IR images obtained by the fabricated FPAs with the 128x128 frame format are demonstrated.
The molecular beam epitaxy (MBE) set-up with analytical control equipment of growth process was designed and fabricated for growing A2B6 compounds including the mercury-containing ones. A technology was elaborated for growing mercury-cadmium-telluride (MCT) solid solution heteroepitaxial structures (HS) by molecular beam epitaxy (MBE) method with a given variation of MCT composition throughout the thickness. HS's MCT MBE on CdZnTe/GaAs substrate with different variation composition in layers at MCT film interfaces were designing and growing. These structures were used for manufacture of high quality single, linear and array photoconductors (PC) and photodiodes (PD) operating at 77K and 200-250K temperature wavelength range of 3-5 micrometers and 8-12$ mum, up and over 20micrometers . Widegap layers at MCT film interfaces are used as passivating coating. Narrowgap layer at MCT film/CdZnTe buffer layers interface is used for decrease of PD series resistance. For decrease of dark currents of photodiodes array operating at 200 K HS MCT MBE were used with special composition distribution of composition throughout the thickness.
The investigation of MBE CdHgTe photodiode characteristics after pressure applying to n-type of junction has been carried out. The diodes parameters have been studied in the temperature range of 5 divided by 120 K. It was found that the mechanical stress causes the increase of traps amount with Et approximately equals Ev plus 0.043 eV and Et approximately equals Ev plus 0.032 eV. The energies of these traps have some temperature dependence. The diodes generation-recombination and trap-assisted tunneling currents significantly increase at forward and reverse biases. The value of RoA decreases in an order at T less than 60 K because of trap assisted tunneling via the dislocation levels. At high temperatures T greater than 60 K the value of RoA does not change and determined by the diffusion mechanism.
The technology was developed and 128 X 128 LWIR FPA's based on HgCdTe epitaxial layers MBE-grown on GaAs substrates with cutoff wavelength (lambda) c equals 8 micrometer and 13 micrometer was fabricated. The photosensing layer HgCdTe was graded-gap layer with the higher content of Cd to boundaries of a layer. The manufactured LWIR FPA's had NETD 32 mK and 17 mK for (lambda) c equals 8 micrometer and 13 micrometer, correspondingly, at 295 K background and 80 K operation temperatures.
Heterostructures HgCdTe/CdTe/GaAs grown by molecular beam epitaxy were used for LWIR FPA fabrication. The technology was developed and 32 by 32 and 128 by 128 photodiode arrays with indium bumps of 15 micrometer height in each pixel were fabricated. Mean NEP is 1.7 by 10-13 W/Hz1/2 and 1.1 by 10-14 W/Hz1/2 for 128 by 128 photodiode arrays with (lambda) c value of 10.4 micrometer and 5.2 micrometer correspondently. The technology of hybrid assembling with continuous control of cold welding on the measuring stand was demonstrated on the example of 32 by 32 LWIR FPA. Mean NEP value of 5.4 by 10-14 W/Hz1/2 with (lambda) c equals 10.6 micrometer at 80 K operation were obtained. using an infrared camera system the infrared image was successfully demonstrated. The NETD value of 0.077 K was obtained under 293 K background condition.
The results of MBE growth of CdHgTe epilayers and fabrication of photosensitive in 8 - 10 mkm region small p-n junctions using planar technology are presented. During MBE epitaxy the growing dynamic, composition and surface roughness were controlled in situ using build in high energy electron diffractometer and ellipsometer. Small area photosensitive diodes (50 X 70 mkm) were fabricated using planar technology and annealing under anodic oxide film. The measurements of V-I, spectral response and noise characteristics showed that the photodiodes on MCT epilayers grown by MBE have an acceptable parameters for fabrication of the linear and 2D photodiode arrays.
We used the heterostructures of HgCdTe/CdZnTe/GaAs grown by molecular beam epitaxy for fabrication of photoconductor devices. The composition of MCT films throughout the thickness was controlled in situ by ellipsometry during the growth process. There were wide band gap layers at the interface and at the surface of the MCT films for decreasing the surface recombination which strongly influences on devices characteristics. The use of n-type material for LWIR photoconductors (77 K, the cutoff wavelength is more than 13 mkm) with good performance was demonstrated. The detectivity in maximum of wavelength dependence varies in interval (1.5 divided by 5)(DOT)1010 cmHz1/2 W-1. P-type material was used for MWIR photoconductors that operated at room and near room temperatures with the close to the theoretical value detectivity.
The results of modeling and experimental investigations of a linear induction accelerator (LIA) operating with relativistic magnetron as a load are discussed in this report. The mathematic model of the LIA injector section is based on the substitution of all main LIA section parts by equivalent circuits. Satisfactory model quality and reliability of the simulation results are confirmed by good agreement of the calculation results with the experimental data obtained by LIA section operation on the electron beam and resistive load. During the simulation a relativistic magnetron model was used in which the self-consistent effective amplitude of the microwave field fundamental harmonic and, accordingly, the generated power are defined by forming voltage and input current, taking into account output current losses. Optimization of a `power supply -- microwave generator' as the unified system on efficiency and generated power will allow us to define the best characteristics of LIA elements and the relativistic magnetron parameters.
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