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排序方式: 共有44条查询结果,搜索用时 31 毫秒
1.
O. Gravrand E. De Borniol S. Bisotto L. Mollard G. Destefanis 《Journal of Electronic Materials》2007,36(8):981-987
This paper aims at studying the feasibility of very long infrared wavelength (VLWIR) (12–18 μm) focal plane arrays using n-on-p planar ion-implanted technology. To explore and analyze the feasibility of such VLWIR detectors, a set of four Cd
x
Hg1−x
Te LPE layers with an 18 μ cutoff at 50 K has been processed at Defir (LETI/LIR–Sofradir joint laboratory), using both our “standard” n-on-p process and our improved low dark current process. Several 320 × 256 arrays, 30-μm pitch, have been hybridized on standard Sofradir readout circuits and tested. Small dimension test arrays characterization
is also presented. Measured photonic currents with a 20°C black body suggest an internal quantum efficiency above 50%. Typical
I(V) curves and thermal evolution of the saturation current are discussed, showing that standard photodiodes remain diffusion
limited at low biases for temperatures down to 30 K. Moreover, the dark current gain brought by the improved process is clearly
visible for temperatures higher than 40 K. Noise measurements are also discussed showing that a very large majority of detectors
appeared background limited under usual illumination and biases. In our opinion, such results demonstrate the feasibility
of high-performance complex focal plane arrays in the VLWIR range at medium term. 相似文献
2.
3.
F. Pedraza M. Mollard B. Rannou B. Bouchaud J. Balmain G. Bonnet 《Oxidation of Metals》2016,85(3-4):231-244
Thermal barrier coatings were synthesized in a single step process from a slurry containing Al microspheres onto different Ni-based superalloys. Upon growth of the coating a top coat of hollow alumina spheres linked to an aluminium diffused coating through an alumina TGO formed. The isothermal and cyclic oxidation tests at different temperatures (900 till 1100 °C) up to 1000 h or 1500 cycles revealed progressive growth of different thermal oxides depending on the substrate composition. Faster degradation of the coatings occurred in the titanium-rich substrates (e.g. IN-738LC and PWA1483) compared to the titanium-poor ones (CM-247LC and René N5). By comparing with conventional low activity aluminide coatings, it appeared that the incorporation of alloying elements (notably Ti and Ta) to the diffused layers upon the high activity slurry coating process is responsible for such fastest degradation. 相似文献
4.
Saturation magnetization of γFe2O3 has been measured at 4.2 kelvin in high magnetic fields on carefully controlled samples by differential thermal analysis, thermogravimetric analysis and X-ray diffraction. Authors give a new value of bulk magnetization of γFe2O3 that takes into account surface state effects and that is not too perturbed by sintering effects. 相似文献
5.
Francois R. Mollard Merton C. Flemings Eisuke F. Niyama 《JOM Journal of the Minerals, Metals and Materials Society》1987,39(11):34-34
The understanding and control of fluidity is, and has been, a major aspect of foundry technology development. This paper reviews the progress made in this area over the years as it applies to aluminum castings. As a result of this development, thin-wall, high-integrity aluminum castings which were previously not thought possible have been produced. Further work in this area is expected to allow metal-matrix composites to fulfill their technical and economic promise. 相似文献
6.
Gwladys Perrais Sophie Derelle Laurent Mollard Jean-Paul Chamonal Gerard Destefanis Gilbert Vincent Sylvie Bernhardt Johan Rothman 《Journal of Electronic Materials》2009,38(8):1790-1799
The impulse response in frontside-illuminated mid-wave infrared HgCdTe electron avalanche photodiodes (APDs) has been measured
with localized photoexcitation at varying positions in the depletion layer. Gain measurements have shown an exponential gain,
with a maximum value of M = 5000 for the diffusion current at a reverse bias of V
b = 12 V. When the light was injected in the depletion layer, the gain was reduced as the injection approached the N+ edge
of the junction. The impulse response was limited by the diode series resistance–capacitance product, RC, due to the large capacitance of the diode metallization. Hence, the fall time is given by the RC constant, estimated as RC = 270 ps, and the rise time is due to the charging of the diode capacitance via the transit and multiplication of carriers
in the depletion layer. The latter varies between t
10–90 = 20 ps (at intermediate gains M < 500) and t
10–90 = 70 ps (at M = 3500). The corresponding RC-limited bandwidth is BW = 600 MHz, which yields a new absolute record in gain–bandwidth product of GBW = 2.1 THz. The increase
in rise time at high gains indicates the existence of a limit in the transit-time-limited gain–bandwidth product, GBW = 19 THz.
The impulse response was modeled using a one-dimensional deterministic model, which allowed a quantitative analysis of the
data in terms of the average velocity of electrons and holes. The fitting of the data yielded a saturation of the electron
and hole velocity of v
e = 2.3 × 107 cm/s and v
h = 1.0 × 107 cm/s at electric fields E > 1.5 kV/cm. The increase in rise time at high bias is consistent with the results of Monte Carlo simulations and can be
partly explained by a reduction of the electron saturation velocity due to frequent impact ionization. Finally, the model
was used to predict the bandwidth in diodes with shorter RC = 5 ps, giving BW = 16 GHz and BW = 21 GHz for x
j = 4 μm and x
j = 2 μm, respectively, for a gain of M = 100. 相似文献
7.
L. Mollard G. Destefanis N. Baier J. Rothman P. Ballet J. P. Zanatta M. Tchagaspanian A. M. Papon G. Bourgeois J. P. Barnes C. Pautet P. Fougères 《Journal of Electronic Materials》2009,38(8):1805-1813
This paper reviews recent developments in the characterization of planar p-on-n photodiodes fabricated from long- and mid-wavelength Hg1−x
Cd
x
Te at␣the Electronics and Information Technology Laboratory (LETI). The Hg1−x
Cd
x
Te epitaxial layers were grown by both liquid-phase and molecular-beam epitaxy. Planar p-on-n photodiodes were fabricated by arsenic implantation into an indium-doped Hg1−x
Cd
x
Te base layer. Electro-optical characterization on these p-on-n photodiodes showed low leakage currents (shunt resistance > 10 GΩ) and mean R
0
A values comparable to the state of the art, i.e., equal to 5000 Ω cm2 at λ
c = 9.3 μm (λ
c: cutoff wavelength). Results of focal-plane arrays operating in both the long-wavelength infrared (IR) and middle-wavelength
IR bands are reported, with noise equivalent delta temperature and responsivity values at λ
c = 9.3 μm in excess of 99.64%. These results demonstrate the viability and technological maturity of both material growth and device
processing. 相似文献
8.
9.
A. Causier I. Gerard M. Bouttemy A. Etcheberry C. Pautet J. Baylet L. Mollard 《Journal of Electronic Materials》2011,40(8):1823-1829
The ability to pattern HgCdTe surfaces using a wet etching solution is an important challenge for processing of third-generation
infrared detectors. The reduction of pixel size, the increase of pixel density, and two-color array technology require perfectly
mastered etching to remove very thin layers and to control the state of the surface. To perform this process, a new quantitative
chemical approach was developed to carry out very accurate wet etching in aqueous HBr/Br2 solutions. This approach was established to identify the key parameters that govern the etching process and to understand
the etching mechanism. 相似文献
10.
O. Gravrand G. Destefanis S. Bisotto N. Baier J. Rothman L. Mollard D. Brellier L. Rubaldo A. Kerlain V. Destefanis M. Vuillermet 《Journal of Electronic Materials》2013,42(11):3349-3358
The purpose of this paper is to review the trends in HgCdTe research, illustrating the discussed ideas with the latest results obtained at DEFIR (CEA-LETI and Sofradir joint laboratory). The beginning of this paper is devoted to an extended introduction to today’s issues concerning HgCdTe photodiode performance enhancement. In fact, very high-quality material is mandatory for ultrahigh performance at low temperature as well as for high noise operability at high operating temperature (HOT). Therefore, a strong effort has been carried out during the last few years for lattice-matched CdZnTe substrate and HgCdTe active layer growth improvement, leading to very large substrates and ultraflat liquid-phase epitaxy layers. The same analysis holds for diode process quality and passivation. Therefore, the photodiode process has been completely revisited in order to optimize HOT operability. Also necessary for the next generation of HOT devices, some significant progress has been made in small-pixel-pitch interconnection on silicon read-out circuits. Indeed, the first 10-μm focal-plane arrays (FPAs) have been successfully fabricated this year in the mid-wave infrared (IR) band. The latest avalanche photodiode (APD) realizations are also presented with 15-μm-pitch FPAs for passive imaging and 30-μm-pitch ultrafast arrays running at 1.5 kHz full frame rate. Linear-mode photon counting using APDs is also briefly discussed. Finally, the paper concludes on more complex structures for the third generation of IR detectors, discussing the latest achievements in dual-band FPA fabrication in various spectral bands. 相似文献