close

Вход

Забыли?

вход по аккаунту

?

el%3A19820411

код для вставкиСкачать
moulding conditions especially decreased dimensional distribution, such as ferrule offroundness and diameter. All moulded ferrules had an offroundness of less than 1 /un and diameter distribution within +1 /im, as shown in Fig. 2. Additionally, by fitting a ring gate on the die, resin was transferred
uniformly into the cavity, and the fine pin in the bottom was
held firmly without being bent. The improved die structure
produced quite small angular error for the fibre incorporated
in the plug ferrule. Average angular misalignments between
fibre and plug ferrule axis was 0-4 deg. The maximum was 1
deg, as shown in Fig. 3.
60 r
References
1
SUZUKI, N., IWAHARA, Y., SARUWATARI, M., and
NAWATA, K. :
'Cer-
amic capillary connector for 1-3 /im single-mode fibres', Electron.
Lett., 1979,15, pp. 809-810
2 NAWATA, K.: 'Multiple and single-mode fiber connectors technology', IEEE J. Quantum Electron., 1980, QE-16, pp. 618-627
3 CHEUNG, N. K.: Transfer-moulded biconical connector for singlemode fiber interconnections'. IOOC, 1981, technical digest, pp. 98
4
KUROKAWA, T., YOSHIZAWA, T., NARA, S., a n d KATAYAMA, Y.: ' P r e -
cision moulded fibre connector using an electroformed cavity'.
Electron. Lett., 1981,17, pp. 667-669
0013-5194/82/140598-02$!. 50/0
n=160
20
0
AMORPHOUS-SILICON SILICON-NITRIDE
FIELD-EFFECT TRANSISTORS
0
1
angular errors, degree
2
i$85;3j
Indexing terms: Semiconductor devices and materials, Fieldeffect transistors
Fig. 3 Angular error of plug ferrules
As improved results, almost all moulded ferrules had sufficient precision for single-mode fibre connection, especially
concerning eccentricity and angular errors.
Assembly and loss measurement: All connector parts were
plastic-moulded, except for a spring coil. Ferrules and sleeves,
which need quite high accuracy, were transfer-moulded using
the phenolic resin. Other plastic parts, which were used to
construct the connector housing, were injection-moulded
using thermoplastic resin. Connectors are for field assembly,
so that fibres must be inserted in the microholes in ferrules
without producing any excess eccentricity. The clearance between the inner hold and the fibre outer diameter was reduced
to below 1 /an. The tip of the plug ferrule, which was polished,
was guided into the adaptor of the female receptacle. They
were assembled easily using adhesive.
The single-mode fibre used had a 10 /im core and 125 /im
outer diameter. Its cutoff wavelength is 115 /im and the
refractive-index difference was 0-3%. The distribution of connection loss is plotted in Fig. 4. The loss was measured
through a 500 m-long dummy fibre between a laser diode
(/ = 1-3 /im) and the connector. An average loss of 0-48 dB
was obtained using a matching oil.
30
20
n = 91
n-channel and p-channel amorphous-silicon field-effect transistors have been fabricated on a glassy substrate using undoped and impurity-doped a-Si films as the semiconductor
and silicon nitride deposited from an SiH^-Nj mixture as the
gate insulator. A change in the source-drain conductance of
greater than four orders of magnitude is realised by changing
the gate potential from 0 to 5 V.
There has been much interest in the properties of amorphous
silicon field-effect transistors (FET) for application in an addressable matrix of a liquid-crystal display panel. The first
anouncement has been made by Le Comber et al.,x who used
silicon nitride as the insulator and a glass plate as the substrate. Very recently they have improved the performance of
their FETs and applied them to several integrated circuits.2 A
very-high-performance FET has been reported by Powell et
a/.,3 who also used silicon nitride as the insulator and a n n +
single-crystal silicon wafer as the substrate. Both groups have
produced these silicon nitride films by the decomposition of a
mixture of SiH4 and NH3 in an RF glow discharge. In this
letter, we report the characteristics of an a-Si FET fabricated
on a glassy substrate using silicon nitride deposited from a
mixture of SiH4 and N2 in the RF glow discharge as the
insulator, for which an on-off current ratio of 104 with the
application of 5 V to the gate has been realised. The use of the
SiH4-N2 gas mixture is desirable since N2 is easier to handle
in a vacuum system than NH3 and a purer source gas is
available.
a-Si
I 10
0
source (AD
05
10
connection loss.dB
nitride
drain (Al)
1-5
BBS^I
Fig. 4 Connection loss of precision-moulded connector
Moulded ferrules had sufficient dimensional stability to
withstand environmental tests. The variation in ferrule diameters after the heat cycle test (-20°C ~ +60°C, 10 cycles) and
the high temperature test (80°C) was less than 0-5 /im. Similarly, no significant loss increment was observed for the environmental tests. The connecting loss fluctuation was within
±01 dB during the heat cycle test.
T. YOSHIZAWA
T. KUROKAWA
S. NARA
Ibaraki Electrical Communication Laboratory
Nippon Telegraph & Telephone Public Corporation
Tokai, Ibaraki 319-11, Japan
2nd June 1982
ELECTRONICS LETTERS 8th July 1982
Vol. 18 No. 14
substrate
Fig. 1 Cross-sectional view of the a-Si FET
Fig. 1 shows schematically the present FET structure. A
glass substrate (for convenience a fused quartz plate is used)
carries a thin evaporated Mo stripe about 100 /im wide, which
forms the gate electrode. The surface is covered with a film of
silicon nitride (about 0-3 /im thick) grown by plasma decomposition of a mixture of 10% SiH4 in H2 and N 2 . During
the deposition of the silicon nitride, the temperature of the
substrate is kept at 300°C. An a-Si layer (about 0-3 /im thick)
is then deposited onto the silicon nitride again by plasma
decomposition of 10% SiH4 in H 2 . Undoped and slightly
599
phosphorus or boron-doped a-Si layers have been used. These
deposition conditions are summarised in Table 1. The properties of silicon nitride films are critically sensitive to the deposition conditions. It is also important to deposit silicon nitride
and a-Si films successively without breaking the reaction
system. Conventional photolithography is used to define the
source and drain contact of evaporated Al. The channel length
is 10 /mi and the channel width is 1 mm or 1-7 mm.
same level as that of the FET reported by Snell et al.2
Valuable discussions with Prof. Y. Shibata and M. Koyama
are gratefully acknowledged. Thanks are also due to H.
Yagami and S. Imagi for their helpful assistance.
10
Vg = 10V
Table 1 DEPOSITION CONDITIONS OF
SILICON NITRIDE AND a-Si FILMS
Silicon nitride
2
RF power density
Substrate temperature
Pressure
Gas flow rate
SiH4 (10% in H2)
N 2 (100%)
Dopant
io 6
a-Si
0-7 W/cm
300°C
10 torr
013 W/cm2
250°C
2 torr
200 seem
100 seem
200 seem
—
PH 3 or B2H6
—
Fig. 2 is a plot of the source-drain current against the gate
voltage for various doping levels. A high current density is
possible in phosphorus-doped a-Si FETs at the cost of the
decrease of the on-off current ratio. The performance of pchannel FETs is unsatisfactory, which arises from the fact that
hole mobility in a-Si is very low (around 10~4 cm2/Vs). In
moderately doped (about 10" 5 of B2H6) a-Si FET, both nchannel and p-channel operations are observed. It should be
noted that the undoped a-Si FET shows excellent transfer
characteristics in an n-channel mode. The current rises sharply
by about four orders of magnitude for a change in the gate
voltage of 5 V. This conductance modulation is sufficient for
an addressable matrix application of a liquid-crystal display
panel.
n- channel
p-channel
«,68
-10
10
7 ^
"-
r
I
—
_/
ov
-12
10
10
V5d. volts
f567/3l
Fig. 3 Source-drain current as a function of drain voltage for undoped
a-Si FET
K. KATOH
M. YASUI
Research & Development Lab.
Stanley Electric Co.
Midori-ku, Yokohama 227, Japan
26th May 1982
H. WATANABE
Sendai Radio Technical College
Kami-Ayashi, Miyagi 989-31, Japan
10
References
1
LE COMBER, p. G., SPEAR, w. E., and GHAITH, A. : 'Amorphous-silicon
field-effect device and possible application', Electron. Lett., 1979,
15, pp. 179-181
2
108
Xx"
SNELL, A. } . , SPEAR, W. E., LE COMBER, P. G., a n d MACKENZIE, K.:
'Application of amorphous silicon field effect transistors in integrated circuits', Appl. Phys., 1981, A26, pp. 83-86
. 1 0 *
3
POWELL, M. J., EASTON, B. c , and HILL, o. F.: 'Amorphous silicon-
silicon nitride thin-film transistors', Appl. Phys. Lett., 1981, 38, pp.
794-796
-5
2x10
0013-5194/82/140599-02$1.50/0
\
-10
10
-5
10
Vg. volts
1567/21
Fig. 2 Source-drain current plotted logarithmically as a function of
positive and negative gate voltages for n-channel and p-channel FETs
Source-drain voltage is 5 V
PH 3 -doped
B 2 H 6 -doped
SOLUTION TO INSTABILITY PROBLEMS
OF GRID-CONNECTED PWM DC-AC
INVERTERS
Indexing terms: Circuit theory and design, Inverters
The stability properties of the forward and the flyback inverter are compared. A free-running inverter is not suited for
grid-connected applications. The realisation of a high opencircuit gain in a system with an externally determined switching frequency and without the loss of the power capacity is
discussed. A 250 W low-distortion grid-connected forward
inverter has been realised.
Fig. 3 shows the corresponding source-drain current against
the drain voltage characteristics for the undoped a-Si FET.
The transistor is operating in the enhancement mode, and the
characteristics are nearly the same as those of a conventional
MOSFET. The calculation of the transfer conductance of
FET gm would give a value of 015 /xQ"1 at the tentative point
The energy transfer between a photovoltaic solar panel and
of Vsd = 5 V and Vg = 5 V. This performance is nearly the the grid can be realised by means of a DC-AC inverter. The
600
ELECTRONICS LETTERS 8th July 1982
Vol. 18 No. 14
Документ
Категория
Без категории
Просмотров
2
Размер файла
251 Кб
Теги
3a19820411
1/--страниц
Пожаловаться на содержимое документа