A ternary solution of mercury–cadmium–telluride (MCT, HgCdTe) is one of the few semiconductor materials used to design photodiodes with high parameters. An estimated calculation of the parameters of ...a promising
P
+
-ν(π)-
N
+
-photodiode structure based on MCT that is designed to build arrays of photosensitive elements (PSEs) with a low dark current was carried out. The dark current is reduced by using an improved three-layer architecture consisting of highly doped MCT contact layers, between which there is a lightly doped absorbing layer, in which thermal generation-recombination processes are suppressed. Thus, in a specified spectral range, the dark currents of PSEs based on the three-layer MCT architecture decrease to the limit set by the background radiation and the radiative recombination mechanism and, under the condition of complete depletion of the absorption region, to a value determined by the Shockley–Read–Hall generation-recombination mechanism.
Dark currents in advanced architecture of a photodiode matrix based on a CdHgTe ternary compound designed to record weak infrared radiation are analyzed. The formation of regions of opposite ...conductivity in the wide-gap layer reduces the contribution of Shockley–Reed–Hall generation–recombination currents, thus increasing the influence of Auger mechanisms that determine the current of diffusion. Using areas of different composition with transition sublayers with a reduced surface recombination rate at the interface, it is possible to reduce the contribution of surface mechanisms to the total dark current of the photodiode. Due to the correct choice of the composition of the absorption region and the upper wide-gap layer in the advanced PSE architecture, it is possible to achieve a decrease of the dark current, and therefore, to improve the photovoltaic parameters.
Dark current is the main factor that influences photodiode performance. It should be minimal to reduce noise and ensure a high level of photoelectric parameters. In order to identify the predominant ...causes of generation–recombination in photodiodes based on a mercury–cadmium–tellurium (MCT) ternary compound in the given voltage range, a calculation model is proposed for dark currents caused by fundamental and other current mechanisms. The components of dark current in photodiodes based on MCT heterostructures grown by molecular beam epitaxy (MBE) and liquid-phase epitaxy (LPE) methods are determined in the reverse bias voltages range from 0 to 40 mV. In the range from 0 to 20 mV, these characteristics are reduced to the diffusion component. When the reverse bias voltage exceeds 30 mV, an increase in the Shockley–Read–Hall (SRH) generation–recombination current and tunneling current through trap levels in the band gap is observed.
The surface recombination rates for
p
-type HgCdTe layers with different dopant concentrations and trap densities
N
t
are calculated. It is shown that, at the given initial parameters, the surface ...recombination rate
S
max
lies in the range of 10–10
4
cm/s. The current sensitivity for
p
-type HgCdTe is simulated using the dependence of quantum efficiency in the approximation of large lifetimes τ
n
0
and large diffusion lengths
L
n
of minority charge carriers, taking into account the effect of the surface recombination rate.
The temperature dependence of the dark current in InAsSb-based
p
–
n
photodiodes detecting radiation in the medium-wave infrared (MWIR) region have been calculated, taking into account material ...characteristics of InAs
1 –
x
Sb
x
alloy. The desired signal-to-noise ratio is ∼10
3
at
T
= 150 K, which confirms the possibility of achieving high photovoltaic parameters in InAs
1 –
x
Sb
x
photodiodes and their usage in high-temperature applications.
Multilayer structures based on semiconductor materials of the antimonide group with InSb and Al
x
In
1 –
x
Sb absorbing layers, including structures with an InAlSb barrier layer (InSb/InAlSb/InSb), ...designed for the manufacturing of advanced photodetectors (PDs) that detect radiation in the mid-wave infrared (IR) range. On the basis of
p
–
i
–
n
and barrier structures grown by the MBE method, photosensitive elements (PSEs) of various topologies with InSb and Al
x
In
1 –
x
Sb absorbing layers were fabricated. It is shown that wide-gap Al
x
In
1 –
x
Sb ternary solutions, which detect radiation in the medium-wavelength region of the spectrum, are an alternative to the narrow-gap binary compound InSb, because, due to the wide-gap, photodiodes based on Al
x
In
1 –
x
Sb have lower currents and, therefore, noise. The average values of detectivity
D
* and noise-equivalent temperature difference (NETD) have been measured for various topology photodetectors, so
D
* was more than 10
11
cm W
–1
Hz
1/2
in
p
–
i
–
n
structures, and
D
* exceed of 10
12
cm W
–1
Hz
1/2
in barrier structures.
Values of the absorption coefficient of InGaAs structures grown by means of gaseous-phase epitaxy from metaloranic compounds have been studied and calculated. Experimental data have been compared to ...the theoretical model of the absorption spectrum based on the phenomenon of fundamental absorption and the general theory of direct interband optical transitions. The energy gap width has been graphically calculated from the slope of the experimental absorption characteristic.
—
In the study, a new
р
B
n
-architecture based on a GaAsSb/AlAsSb/InAsSb heterostructure of III‒V group materials with an
n
-type AlAsSb barrier layer, an
n
-type InAsSb absorption layer, and a
р
...-type GaAsSb collector layer, designed for detection of radiation in the mid-wavelength infrared range of 3.1–4.2 µm has been developed and investigated. The proposed structure has no valence band offset, which enables operation in a wide bias voltage range without depletion of the base
n
-type InAsSb active layer. The barrier in the conduction band, due to the presence of a wide-gap AlAsSb layer in the structure, is ∼1.0 eV, which is sufficient to eliminate the electron current component. The dark currents and performance of the
р
B
n
-structure have been analyzed, with the result that, at an operating temperature of
Т
≈ 150 K and dark current density of
J
≤ 6 × 10
–10
A/cm
2
, the detectivity value reaches
D
* ≥ 2.5 × 10
12
(cm W
–1
Hz
1/2
).
Modern Photodetector IR-Modules Boltar, K. O.; Burlakov, I. D.; Iakovleva, N. I. ...
Journal of communications technology & electronics,
09/2022, Letnik:
67, Številka:
9
Journal Article
Recenzirano
In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of advanced materials; designing the structure of a ...photosensitive element (PSE) to achieve the minimum dark current, which in turn leads to a change in generations of matrix photodetector modules (PDMs). Several different types of PDMs based on InSb epitaxial structures for the range of 3–5 μm, based on GaAs/AlGaAs QWIP-structures for the range 7.8–9.0 μm, and based on InGaAs
X
B
n
-structures for the range 0.9–1.7 μm were developed and investigated. The foreign analogs are shown, and the advantages given by the new capabilities offered by new detector technologies are considered.
We report on the investigations of focal plane arrays for mid-wave infrared radiation detection based on antimonide multilayers with InSb, Al
x
In
1 –
x
Sb, and InAs
1 –
x
Sb
x
absorption layers, ...including structures with InAlSb (InSb/InAlSb/InSb) and InAsSb (InAsSb/AlAsSb/InAsSb) barrier layers for optoelectronic systems and equipment. Photosensitive elements of different topologies have been fabricated. It has been demonstrated that wideband Al
x
In
1-x
Sb and InAs
1 –
x
Sb
x
ternary alloys are an alternative to the narrowband InSb binary compound, since the photodiodes based on them exhibit lower dark currents and, consequently, low noise. The average values of detectivity
D
* and noise equivalent temperature difference for the photodetectors based on photosensitive element arrays of different topologies have been measured.
