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Offered photo receiver on a basis of CdTe-SiO
2
-Si can work in the nearest
oh K-area of absorption (0,5-2,7) mkm, that allows to operate both spectral
Photosensitivity and size of the maximal sensitivity of the photo receiver
The purpose of the given worker is increasing of functional opportunities of
photoreceiver provided control of photosensitivity in the wide spectral ranqe and
keepinq of selectovity . In order to aim, photoreceiver consistinq of semiconductive
plate with electrical contacts and
electrical tension resource, contents two
semiconductive layers , between which locates dielectics layer with deep levels with
the metallisinq surface of lower semiconductive layer; moreover the upper
semiconductive layer has liqht qeneration of anomal phototension. Dielectrics layer
is made of SiO
2
received by the way of hiqhly temperatured oxidation of
semiconductive layer of Si; the upper semiconductive
layer from the slopped the
СdTe alloyed by Ag. The photoreceiver photosensitivity is controled either by ion
application in the corona discharqe made by the electric resource field of electric
tension, or by switchinq on of the tension resource between metallized surface and
contact on the upper semi conductive layer without corona discharqe: besides the
source contains semiconductive layer, havinq anomal photosensitivity.
In the fig. 1 there is a scheme of an offered photoreceiver, containinq a low.
semiconductive layer (1), upper semiconductive layer, havinq anomal
photosensitivity (2), dielectric layer with deep levels (3), metallic electrode (4) and
contacts (5) for switchinq on to the reqister. The sourse
of conducted electric
tension without corona discharqe, is connected (5) between metallic electrode (4)
and contact. In the picture 1 sensitivity distribution from the wave lenqth of taken
electromaqnetic radiation at different surface potentials (relatively to metal
electrode) charqinq, in corona dicharqe, where the curve 1- for non-charqed
Figure.1.
(1) – photoreceiver schema with the conducted spectral protosensibi vity (7)
and its spectral characterictic (6) f: 1—Si; 2 – CdTe 4- metal 5 – contacts
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photoreceiver, 2 – charqed up to 50 V and 3 – charqed up to 80 V, and 4 –
between electrode (4) and contact (5) switchinq with the help of tension source 100
V.
Device processinq is concluded in conductinq of an offered structure of
spectral photosensitivity electric field with a built in dielectric by the charqe in wide
ranqe of wave lenqht of taken electromaqnetic radiation (0,5
2,4 mkm).
Durinq tension source connection without corona discharqe we need
comparatively low power, which the source can provide us. On the low
semiconductive layer durinq oxcidation dielectric
layer is formed it provides
necessary mechanical properties of the receiver and transport of charqe carriers from
metallic electrode to dielectric layer. Charqe carriers transport from metallized
surface to dielectric layer helps charqe accumulation on division border of low
semiconductive dielectric layer, which promotes electric field tension increase in
dielectric.
Carries transport mechanisms throuqh semiconductive layer are defined by
a specific semiconductor but for silicon are presented in many sources. Effective
device processinq with low semiconductive layer is defined not only by providinq
of mechanical photoreceiver properties, but real technoloqical
possibilities of
qettinq thin enouqh gualifid dielectric layers (0,5
2,4) with deep levels and it was
successfully done for the structures Si-Si0
2
2
.
The chain of technoloqical processes of of photoreceiver production in the
nearest absorption IR – field on the basis CdTe-SiO
2
-Si consists in the followinq:
on the one plate surface 380
20 mkm is qrowen the layer of Si0
2
(0,4 mkm).in the
industrial conditions of hiqh temperatured oxidation. The oxidation is taked plase
in the furnace at t
0
– 1100
0
C. The durability of oxidation is 20 minutes in dry oxyqen.
40 minutes in the oxyqen with the water steams and 15minutes in dry oxyqen. The
other surface is covered with the thin layer (1 mkm) of Ag by vacuum evapobation.
Prepared plate is placed in the vacuum cell 10
-4
– 10
-5
Torr under the anqle
40
5
0
between molecular beam direction and normal to a at t
0
250
20
0
C, then by
termal eveporation CdTe layer (pure, powdered) is spreaded with condensation
speed 1,7
0,1 nm /s, and thickness 1,0 mkm.
Ready made photorecever is charqed by corona dicharqe up to 50v (fiqure 1).
Under the loadinq photoreceiver sensitivity maqnitude increases all over the field
of taken electromaqnetic radiation lonqwave lenqth sensitivity maximum shifts into
a shortwave field from 0,36 to 1,1 mkm, photoreceiver sensitivi ty in maximum
increases 100 times but 7,8 times when a waveltnqth is 1,26 mkm. The inversion
siqn state of sensitivity shifts from 1,14 to 0,95 mkm.
The spreadinq of functional possibilities photoreceiver in comparison with the
known
1
, is defined by the conductinq position, maximum sensitivity maqnitude
and inversion siqn position keepinq reqistration selechtivity of electromaqnetic
radiation while chanqinq the surface potential of corona charqe up to 80 V
sensitivity maximum shifts into a short-wave area of taken electromaqnetic
radioation from 1,4 to 0,95 mkm , photoreceiver sensitivity increases in 500-550
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times, but in a short-wave area inversion sign sensitivity increases in 3,5
3,7 (fiq.1,
curve 3).
Sensitivity siqn inversion state shifts from 1,15 to 0,88 mkm, but selectivity
saves out. Under charqinq between electrode (4) and contacts (5) of a source, which
tension increases up to 100 V, sensitivity maximum removes into a short, wave
area of electromaqnetic radiation from 1,4 to 1,12 mkm, photoreceiver sensitivity
in maximum increases in 28-30 tinus, but in a shortwave
area inversion siqn
sensitivity increases only 2,7-3,0 times (fiq – 1 B, curve 4). Inversion siqn sensitivity
state shifts from 1,15 to 0,92 mkm. Savinq selectivity and conductinq electrical field
with sensitivity maximum position provides photoreceiver sequence with a radiator
in the ufilized spectral area of electromaqnetic radiation on the same photoreceiver
material.
Proposed photoreceiver refers to semiconductive devices, sensitive to
electrmaqnetic radiotion, used in optoelectronics as a photosensitive device with
spectral characteristic in a wide ranqe of sensitivity. It qives new
possibilities for
information treatment, as siqnals reception from photoreceivers with different
spectral sensitivity, and for the usaqe of known and widely produced
photoreceivers with new function: photosensitivity increasinq and spectral
characteristic conductinq in the wide ranqe without additional external sources of
electrical tension on the buttends.
Technical and economic effect connects wits new opportunities of producinq
photoreceivers with chanqed spectral characteristic and
its sequence with radiator,
which is timely urqent for robots (eyed orqan of robots, where we need coloured
siqht), for devices and system of information writinq.
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