파트넘버.co.kr RN552 데이터시트 PDF


RN552 반도체 회로 부품 판매점

THIN FILM AMORPHOUS SILICON POSITION SENSITIVE DETECTORS



ETC 로고
ETC
RN552 데이터시트, 핀배열, 회로
Thin-Film Amorphous Silicon
Position-Sensitive Detectors
By Jasmine Henry* and John Livingstone
Optical position-sensitive detectors are a useful class of sensor with a wide range of
applications in machine control systems, industrial alignment and robotic vision. They
have distinct advantages over most arrayed discrete optical devices in that they can
produce continuous optical signals, and versions based on thin-film amorphous sili-
con are not restricted by crystal growth limits and so have the potential to be fabri-
cated in large area format. Sputter-deposited hydrogenated a-Si also has features such
as excellent adhesion to glass substrates, precise film thickness, and hydrogen content control, which are of some
interest in device design and fabrication.
1. Introduction
Position-sensitive detectors, or PSDs, comprise an impor-
tant class of optical sensor, producing an electrical output,
either voltage or current, which utilizes the lateral photo-
voltaic effect to give a linear relation between the output and
the location of a spot of light impinging on a semiconductor
surface. This phenomenon was first described by Schottky in
1930[1] and rediscovered by Wallmark in 1957.[2]
PSDs are used for a variety of optical applications, such as
machine tool alignment, medical instrumentation, remote
optical alignment, robotic vision, and other applications
requiring precision measurements. Other interesting applica-
tions include telephone information systems,[3] surface profil-
ing, angle measurement, rotation monitoring, guidance sys-
tems, and roles where precise automated control is necessary.
PSDs are different to photodiode and other device arrays,
e.g., those formed using charge coupled devices (CCDs), in
that they can provide continuous information with no internal
discontinuities.[4] The other advantages of PSDs over CCDs
are that PSDs have better sampling frequencies (10 MHz to
10 kHz compared to 2 kHz) and they are cheaper. CCDs have
the advantage that they are more effective at eliminating the
effects of stray light.[5]
The wavelength sensitivity of these devices is, like all semi-
conductor optical devices, dependent upon the optical energy
gap of the absorbing material so that a typical silicon-based
single-crystal device has a maximum response in the region of
1000 nm. Our a-Si devices appear to have an optimal response
to white light (peak wavelength 690 nm), which corresponds
to an effective energy gap in the region of 1.8 eV. Light inten-
sity does not appear to affect the linearity of device output,
however, the magnitude of the response is directly related to
the input power while operating below optical saturation. The
devices, however, appear to lose linearity close to the contacts
and this is attributed to edge effects related to electric field
distributions.[4]
Typical light saturation for silicon-based PSDs is around
3 W/cm2 and above this figure the photocurrent has a magni-
tude such that the voltage drop across the sheet resistance is
so large that it equals reasonable values of reverse bias across
the device in photodiode mode. At this point the p±n junction
will be forward biased and hence the PSD no longer functions
in this mode. Our devices have shown the best linearities in
photovoltaic mode, with no advantage being gained in photo-
diode mode implying that we are approaching saturation with
some of our optical sources. In a photodiode, saturation
means that the production of photocurrent is saturated and
can no longer increase with increasing light intensity. This
leads to an accumulation of charge in the diode which slows it
down. To remove these charges after the light is turned off, a
recovery time is required.[5]
±
[*] Dr. J. Henry, Dr. J. Livingstone
Department of Electrical and Electronic Engineering
University of Western Australia
35 Stirling Highway, Crawley, W.A. 6009 (Australia)
2. Mechanisms of Position-Sensitive Detector
Operation
The simplest model of a PSD is that of a crystal-based
device with a highly conducting top layer on a lower conduc-
tivity substrate, with appropriately placed contacts. They can
Adv. Mater. 2001, 13, No. 12±13, Julyl 4
Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001 0935-9648/01/12±1307-01 $ 17.50+.50/0
1


RN552 데이터시트, 핀배열, 회로
J. Henry, J. Livingstone/Thin-Film Amorphous Silicon Position-Sensitive Detectors
detect position in either a one-dimensional or a two-dimen-
sional sense.[2] When light is shone onto any p±n junction,
electron±hole pairs are generated on both sides of the junc-
tion and carriers move down the potential gradient, with
minority electrons moving from the p-side to the n-side and
minority holes moving from the n-side to the p-side. This sets
up a forward bias and a transverse photovoltage is set upÐ
this is the basic mechanism of a solar cell output voltage,
when the whole receiver surface is illuminated with light. If
now a spot of light is shone on a junction that has one layer
that is much more conductive than the other, a lateral photo-
voltage is also set up and we can observe a voltage parallel to
the plane of the junction. As before, electrons and holes are
generated on both sides of the junction, and the minority
carriers are swept across the junction. The photogenerated
carriers are swept down the built-in potential to the highly
conducting layer, and spread rapidly in this plane, forming an
equipotential layer. These carriers from the equipotential
layer then re-inject into the less conductive layer. In this low-
conductivity layer, slow-moving excess carriers are still
located in the region of the light spot. It is the tendency of
these bunched carriers to recombine with the re-injected car-
riers that constitute the lateral photovoltage. This photovol-
tage is a measure of the location of the light beam. Further-
more, the linear behavior of the incremental change in the
voltage with distance along the receiver surface indicates the
sensitivity, or the usefulness of the sensor.[6] This is the photo-
voltaic mode and Figure 1 shows a simplified crystalline
example of a PSD in this mode. If however, the device is
reverse biased, re-injection is inhibited by the increased
Fig. 1. A crystalline PSD configured for measurement in photovoltaic mode.
potential barrier, recombination is reduced, and the same con-
tacts can be used to collect currents flowing in the base layer.
In this case, current can be used to measure the location of
the beam. This is the photodiode mode.
Amorphous silicon devices, such as those based on p±i±n
and similar structures, follow the same general principles but
the precise carrier flow mechanisms are more complex. As
with p±i±n solar cells, electron±hole pair generation occurs in
the intrinsic layer and carriers are then separated by the junc-
tion potentials so that electrons move to the n-layer and holes
to the p-layer. These p±i±n structures can be configured as
one- or two-dimensional devices and are widely researched.
Mechanisms and properties of these devices are extensively
discussed in the literature.[4,7±10]
Our work is focused on the optimization of the actual thin-
film PSD structure so that we have concentrated mainly on
one-dimensional devices with some two-dimensional devices
constructed. We have designed a novel configuration compris-
ing an indium tin oxide (ITO) layer, followed by an a-Si film
and a platinum layer, and a typical configuration, which forms
a Schottky barrier device, is shown in Figure 2.
Fig. 2. A typical thin-film Schottky barrier device structure.
3. a-Si-based Position-Sensitive Detectors
PSDs based on crystalline structure have been widely
reported[11] but major drawbacks of these devices are their
limited area and high relative costs. These comparatively
small devices require complex and expensive optical systems
to ensure maximum utilization of their areas and to minimize
inherent discontinuities.[3] Research devices are often made
with pathlengths in the region of 20 mm, while commercial
devices range from 2.5 mm to about 30 mm. Our devices, both
crystalline and amorphous silicon, range from 16 mm to
20 mm by 10 mm.
Thin-film amorphous silicon is a well-established technol-
ogy nmaterial?n used extensively for the fabrication of solar
cells.[12,13] In a position-sensitive detector it can be deposited
as a transparent film, which makes it possible to utilize it for
angular detection.[9] It also has a number of inherent advan-
tages, including low-temperature processing capabilities, high
photosensitivity and short detector response times of ls.[10] Its
main drawback is the high defect state density, which can be
greatly reduced using hydrogenation. Amorphous silicon can
be prepared using many techniques, among the more common
ones are radiofrequency (RF) and direct current (DC) glow
discharge, RF sputtering, chemical vapor deposition (CVD),
plasma-enhanced chemical vapor deposition (PECVD), and
ion discharge. Most of the latest work is on a-Si:H PSDs fabri-
cated using PECVD p±i±n structures.[4,10] These doped struc-
tures produce excellent linearity between voltage output and
position. Of the plasma techniques, glow discharge and sput-
tering, the former has received the most attention probably
due to its ability to produce films with superior optical and
electrical properties[14] but reactive sputtering deposition has
the advantage of permitting good control of the hydrogen
content of the amorphous silicon.[15] Since the hydrogen con-
tent of a-Si:H has a major effect on the optical and electrical
2
Ó WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001 0935-9648/01/12±1307-02 $ 17.50+.50/0
Adv. Mater. 2001, 13, No. 12±13, July 4




PDF 파일 내의 페이지 : 총 4 페이지

제조업체: ETC

( etc )

RN552 detector

데이터시트 다운로드
:

[ RN552.PDF ]

[ RN552 다른 제조사 검색 ]




국내 전력반도체 판매점


상호 : 아이지 인터내셔날

전화번호 : 051-319-2877

[ 홈페이지 ]

IGBT, TR 모듈, SCR, 다이오드모듈, 각종 전력 휴즈

( IYXS, Powerex, Toshiba, Fuji, Bussmann, Eaton )

전력반도체 문의 : 010-3582-2743



일반적인 전자부품 판매점


디바이스마트

IC114

엘레파츠

ICbanQ

Mouser Electronics

DigiKey Electronics

Element14


관련 데이터시트


RN55

Metal Film Resistors - Vishay Siliconix



RN55

Metal Film Resistors - Vishay



RN552

THIN FILM AMORPHOUS SILICON POSITION SENSITIVE DETECTORS - ETC



RN55C10R0BB14143

Metal Film Resistors - Vishay



RN55C10R0BB1488

Metal Film Resistors - Vishay



RN55C10R0BBSL143

Metal Film Resistors - Vishay



RN55C10R0BBSL88

Metal Film Resistors - Vishay



RN55C10R0CB14143

Metal Film Resistors - Vishay



RN55C10R0CB1488

Metal Film Resistors - Vishay