共查询到12条相似文献,搜索用时 0 毫秒
1.
S. Krishnamurthy M. A. Berding H. Robinson A. Sher 《Journal of Electronic Materials》2006,35(6):1399-1402
We have generalized the existing expression for the trap-assisted tunneling current to include the effect of linearly varying
electric field in the depletion region and self-consistently calculated steady-state trap occupation probability. We find
that the magnitude and variation of current with voltage depend critically on these improvements. 相似文献
2.
Bake stability of long-wavelength infrared HgCdTe photodiodes 总被引:2,自引:0,他引:2
A. Mestechkin D. L. Lee B. T. Cunningham B. D. Mac Leod 《Journal of Electronic Materials》1995,24(9):1183-1187
The bake stability was examined for HgCdTe wafers and photodiodes with CdTe surface passivation deposited by thermal evaporation.
Electrical and electrooptical measurements were performed on various long-wavelength infrared HgCdTe photodiodes prior to
and after a ten-day vacuum bakeout at 80°C, similar to conditions used for preparation of tactical dewar assemblies. It was
found that the bakeout process generated additional defects at the CdTe/ HgCdTe interface and degraded photodiode parameters
such as zero bias impedance, dark current, and photocurrent. Annealing at 220°C under a Hg vapor pressure following the CdTe
deposition suppressed the interface defect generation process during bakeout and stabilized HgCdTe photodiode performance. 相似文献
3.
VLWIR HgCdTe detector current-voltage analysis 总被引:1,自引:0,他引:1
Angelo Scotty Gilmore James Bangs Amanda Gerrish 《Journal of Electronic Materials》2006,35(6):1403-1410
This article details current-voltage characteristics for a very long wavelength infrared (VLWIR) Hg1−x
CdxTe detector from Raytheon Vision Systems with a cutoff wavelength of 20.0 μm at 28 K. In this article, the VLWIR detector
diode currents are modeled as a function of bias and temperature. This in-depth current model includes diffusion, band-to-band
tunneling, trap-assisted tunneling (TAT), and shunt currents. The trap density has been extracted from the modeled TAT component
of the current and was revealed to be relatively temperature-independent. An attempted incorporation of VLWIR detector susceptibility
to stress has also been included through variation of the model parameter associated with the p-n junction electric field
strength. This field variation accounts for stress induced piezoelectric fields. The current in this VLWIR detector was found
to be diffusion-limited under much of the temperature and bias ranges analyzed. This modeling allows the scrutiny of both
the dominant current-limiting mechanism and the magnitudes of the various current components as a function of both bias and
temperature, allowing the straightforward determination of the ideal operating conditions for a given detector. 相似文献
4.
E. P. G. Smith G. M. Venzor P. M. Goetz J. B. Varesi L. T. Pham E. A. Patten W. A. Radford S. M. Johnson A. J. Stoltz J. D. Bensen J. H. Dinan 《Journal of Electronic Materials》2003,32(7):821-826
A combination of mechanical experiments and fabrication of very-long-wavelength infrared (VLWIR) HgCdTe-infrared detectors
has been used to investigate the interaction between various unit-cell design and dry-etch process variables on final unit-cell
dimensions and detector performance. Etch rate, which determines the process time required to achieve a specified etch depth,
was found to be a function of both the trench width opening used to delineate an individual detector element in a focal-plane
array (FPA) and the mesa profile observed during etching. Current-voltage (I-V) probe data at 78 K demonstrated the successful
fabrication of 30 μm unit-cell, VLWIR-HgCdTe diodes with mesa delineation performed by dry etching. The breakdown performance
of these diodes is sensitive to trench width and dry-etch process time. 相似文献
5.
In this paper we report the calculated results of the dark current and multiplication factor in MBE grown HgCdTe avalanche
photodiodes with separate absorption and multiplication (SAM-APD). The device architecture used for this analysis comprises
the following layers: p+ contact, p junction, n− multiplication, n charge sheet, n− absorber, and n+ contact. Various leakage current mechanisms are considered and the generation-recombination term is found to be the dominant
one for this device structure. However, experimental reverse bias I-V characteristics reported earlier by T. de Lyon et al.
shows a large deviation from ideality, which can not be explained in terms of bulk leakage current mechanism. To explain the
large difference between experimental and theoretical data we consider that the dominant generation-recombination current
is multiplied through impact ionization process. To validate this assumption, multiplication is calculated as a function of
reverse bias. Electric field profile is obtained and the multiplication is computed using the ionization coefficients and
avalanche gain equations. Breakdown voltage is found to be 85 V for room temperature operation in agreement with available
data in the literature. The theoretical I-V curves considering multiplication are compared with the experimental ones and
a close agreement is found which validate this model. 相似文献
6.
HgCdTe electron avalanche photodiodes 总被引:1,自引:0,他引:1
M. A. Kinch J. D. Beck C. -F. Wan F. Ma J. Campbell 《Journal of Electronic Materials》2004,33(6):630-639
Exponential-gain values well in excess of 1,000 have been obtained in HgCdTe high-density, vertically integrated photodiode
(HDVIP) avalanche photodiodes (APDs) with essentially zero excess noise. This phenomenon has been observed at temperatures
in the range of 77–260 K for a variety of cutoff wavelengths in the mid-wavelength infrared (MWIR) band, with evidence of
similar behavior in other IR bands. A theory for electron avalanche multiplication has been developed using density of states
and electron-interaction matrix elements associated with the unique band structure of HgCdTe, with allowances being made for
the relevant scattering mechanisms of both electrons and holes at these temperatures. This theory is used to develop an empirical
model to fit the experimental data obtained at DRS Infrared Technologies. The functional dependence of gain on applied bias
voltage is obtained by the use of one adjustable parameter relating electron energy to applied voltage. A more quantitative
physical theory requires the use of Monte Carlo techniques incorporating the preceding scattering rates and ionization probabilities.
This has been performed at the University of Texas at Austin, and preliminary data indicate good agreement with DRS models
for both avalanche gain and excess noise as a function of applied bias. These data are discussed with a view to applications
at a variety of wavelengths. 相似文献
7.
Angelo Scotty Gilmore James Bangs Amanda Gerrish 《Journal of Electronic Materials》2005,34(6):913-921
An automated iterative nonlinear fitting program has been developed to model current-voltage (I–V) data measured on HgCdTe
infrared (IR) detector diodes. This model includes the ideal diode diffusion, generation-recombination, band-to-band tunneling,
trap-assisted tunneling (TAT), and avalanche breakdown as potential current limiting mechanisms in an IR detector diode. The
modeling presented herein allows one to easily distinguish, and more importantly to quantitatively compare, the amount of
influence each current limiting mechanism has on various detectors’ I–V characteristics. Longer cutoff wavelength detectors
often exhibit significant current limitations due to tunneling processes. The temperature dependence of these tunneling characteristics
is thoroughly investigated for two diodes. 相似文献
8.
Laser-beam-induced current (LBIC) is being investigated as an alternative to electrical measurements of individual photodiodes
in a two-dimensional array. This is possible because LBIC only requires two electrical contacts to an array and the two-dimensional
scanning of a focused laser beam across the array to image the entire array. The measured LBIC profiles, obtained from linear
arrays of HgCdTe photodiodes, will be used to study the uniformity of photodiodes in the array and to extract the R0A of the photodiodes. It will be shown that the shape of the LBIC signal is correlated to the electrical performance of the
photodiode, with R0A related to the spreading length of the photodiodes. Linear arrays of n-on-p, mid-wavelength infrared (MWIR) and long wave-length
infrared (LWIR) devices were formed in liquid-phase epitaxy HgCdTe epilayers using a plasma junction-formation technique.
The LBIC profiles were measured on each of the devices at various temperatures. For the MWIR devices, the extracted spreading
length shows no correlation with R0A. However, the LBIC signal does detect nonuniform devices within the array. For the case of the LWIR devices, the spreading
length is extracted as a function of temperature, with the R0A subsequently calculated from the spreading length. The calculated R0A, obtained without requiring contact to each photodiode in the array, agrees well with electrical measurements. Asymmetry
of the LBIC signals for certain devices in the arrays is shown to be a result of localized leakage at the photodiode junction
or from the contact pads through the passivation layers. These results are confirmed by numerical modeling of the device structures. 相似文献
9.
Effects of hydrogen on majority carrier transport and minority carrier lifetimes in long-wavelength infrared HgCdTe on Si 总被引:4,自引:0,他引:4
P. Boieriu C. H. Grein J. Garland S. Velicu C. Fulk A. Stoltz L. Bubulac J. H. Dinan S. Sivananthan 《Journal of Electronic Materials》2006,35(6):1385-1390
We present extended results on the use of a hydrogen plasma to passivate the effects of defects in long-wave ir HgCdTe/Si.
Annealed and as-grown epilayers, in situ doped with indium, were exposed to a hydrogen plasma generated in an electron cyclotron
resonance (ECR) reactor. Secondary ion mass spectrometry was used to measure the extent of hydrogen incorporation into the
epilayers. Hall and photoconductive lifetime measurements were used to assess the efficacy of passivation. The passivation
of defects responsible for the scattering and recombination of electrical carriers was observed for most ECR conditions over
a range of dislocation densities. 相似文献
10.
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
11.
L. S. Hirsch K. S. Ziemer M. R. Richards-Babb C. D. Stinespring T. H. Myers Thierry Colin 《Journal of Electronic Materials》1998,27(6):651-656
Reflection high energy electron diffraction (RHEED) patterns of HgCdTe surfaces etched with bromine methanol are diffuse with
a faint ring pattern indicative of an overlayer consisting of a mixture of oxides and amorphous Te. Exposure to an atomic
hydrogen flux results in a RHEED pattern indicative of a high quality, two-dimensional surface. Atomic force microscopy (AFM)
measurements indicate a rms surface roughness less than 1 nm. CdTe grown on this surface at 80°C maintains the streaky RHEED
pattern and smooth surface as indicated by AFM. X-ray photoelectron spectroscopy measurements indicate that the etched surfaces
contain both an oxide layer and a metallic Te overlayer which were removed by continued exposure to atomic hydrogen. Further
exposure results in significant HgTe depletion, which appears to be a near-surface phenomenon. Preliminary device results
indicate that use of atomic hydrogen is a viable approach for low temperature cleaning of etched HgCdTe surfaces. 相似文献
12.
C. A. Musca D. A. Redfern E. P. G. Smith J. M. Dell L. Faraone J. Bajaj 《Journal of Electronic Materials》1999,28(6):603-610
A new, nondestructive junction depth measurement technique for HgCdTe photovoltaic devices is investigated. The technique
uses a scanning laser microscope to obtain laser beam induced current (LBIC) data from which information regarding the junction
depth is extracted, and is applicable to both homojunction and heterojunction diodes. For implanted heterojunction photodiodes,
the position of the n-p junction relative to the heterojunction is an important factor determining completed device performance,
with blind photodiodes resulting if the n-p junction is incorrectly placed. At present, the only methods available for junction
depth determination (e.g., secondary ion mass spectroscopy and differential Hall) are destructive and not applicable as routine
process monitoring techniques. It is envisaged that the development of a nondestructive routine process monitoring procedure
will help improve yield and reduce the cost of HgCdTe photovoltaic devices. In this paper, experimental and theoretical results
are presented in order to assess the sensitivity of the new technique to the effects of junction doping density, illumination
wavelength, frontside/backside illumination, and test structure geometry. 相似文献