Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-12-26
2003-12-16
Wilson, Allan R. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S352000
Reexamination Certificate
active
06664597
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a retaining substrate for mounting a semiconductor element thereon and a semiconductor device in which said substrate is used. More particularly, the present invention relates to a insulative retaining substrate for mounting a semiconductor element thereon and which has a function of efficiently performing heat radiation for said semiconductor element mounted thereon and a semiconductor device comprising a semiconductor element mounted on said insulative substrate.
2. Related Background Art
In recent years, the global warming of the earth because of the so-called greenhouse effect to an increase in the content of CO
2
gas in the air has been predicted.
In view of this, there is an increased demand for the development of clean energy sources with no accompaniment of CO
2
gas exhaustion. As one of such clean energy sources, there can be mentioned atomic power generation. However, for the atomic power generation, there are problems which are difficult to be solved, such as radioactive wastes and the like which cause air pollution. Also in view of this, there is an increased demand for providing clean energy sources which are highly safe and do not exhaust air-polluting substances.
Under these circumstances, public attention has now focused on a solar cell which converts sunlight into electric energy as a clean energy source, because it does not exhaust contaminants and it is safe and can be readily handled.
As such solar cell, there are known have a variety of solar cells. And some of them have been using as power generation sources in practice. These solar cells include crystalline series solar cells in which single crystal silicon material or polycrystal silicon material is used, amorphous series solar cells in which amorphous silicon material is used, and compound semiconductor series solar cells in which compound semiconductor material is used. Besides, there are known a variety of configurations for these solar cells to be practically used. Specifically, there are known, for instance, a frame type solar cell as disclosed in Japanese Unexamined Patent Publication No. 82820/1993, a frame-less type solar cell as disclosed in Japanese Unexamined Patent Publication No. 131048/1995, a roofing material-integral type solar cell as disclosed in disclosed in Japanese Unexamined Patent Publication No. 177187/1996 or Japanese Unexamined Patent Publication No. 97727/1999, and an optical-concentration type solar cell as disclosed in Japanese Unexamined Patent Publication No. 83006/1997.
For any of these solar cells, the material cost of the cell (the photoelectric conversion element) constituting the solar cell accounts for the largest rate of the cost of the solar cell. Thus, in order to reduce the cost of the solar cell, it is an important factor to diminish the use amount of the material constituting the cell (the photoelectric conversion element). The optical-concentration type solar cell is of the configuration in that in order to reduce the power generation cost by making full use of the ability of a photoelectric conversion element (a cell) used therein which is costly, sunlight is converged and condensed to several times to several hundreds times by means of a condenser lens to increase the quantity of incident light to the photoelectric conversion element, whereby diminishing the use amount of the photoelectric conversion element.
Specifically, the optical-concentration type solar cell disclosed in Japanese Unexamined Patent Publication No. 83006/1997 is of the configuration in that a solar cell comprising a compound semiconductor material such as GaAs or the like is arranged on a retaining substrate constituted by glass, resin or ceramics, a reverse taper-like concaved portion whose open area being upward widened is arranged above the solar cell, and a light-converging structural body with a high refraction factor and which comprises a resin such as polystyrene and has a surface processed into a lens-like form is accommodated in said concaved portion. Separately, Japanese Unexamined Patent Publication No. 231111/1995 discloses a substrate for an optical-concentration type solar cell. This substrate has a structure in that a plurality of small solar cells are connected respectively to a standard IC-type carrier comprising a dual in-line package or the like and the carriers are attached to a print substrate comprising a throughhole substrate or the like to establish electrical connection between the carriers.
For these solar cells, there is a drawback such that when the temperature of the solar cell is increased, the photoelectric conversion efficiency (the power generation efficiency) is deteriorated. In order to solve such problem, Japanese Unexamined Patent Publication No. 83003/1997 proposes a method in that for a solar cell formed on a substrate, a cooling fin is provided at a said substrate and a ventilation trunk is formed at said substrate to prevent the temperature of the solar cell from being raised.
This cooling method is effective when the solar cell is installed in an environmental atmosphere whose temperature is not remarkably increased. However, in the case of an optical-concentration solar cell, as the light condensation magnitude is increased, the temperature of the solar cell is extremely increased. And it is difficult to sufficiently prevent the extreme temperature rising of the solar cell in this case by aforesaid cooling method.
Detailed description will be made of this point with reference to the drawings.
FIGS.
3
(
a
) to
3
(
d
) are schematic views illustrating the structure of an example of an optical-concentration type solar cell comprising a single crystal silicon material.
Particularly, FIG.
3
(
a
) is a schematic plane view illustrating an appearance of a light receiving face side of the optical-concentration type solar cell, FIG.
3
(
b
) is a schematic view illustrating an appearance of a first side face of the optical-concentration type solar cell, FIG.
3
(
c
) is a schematic view illustrating an appearance of a second side face of the optical-concentration type solar cell, and FIG.
3
(
d
) is a schematic plane view illustrating an appearance of a non-light receiving face side of the optical-concentration type solar cell.
In FIGS.
3
(
a
) to
3
(
d
), reference numeral
1
indicates a photovoltaic element constituted by a single crystal silicon material, and reference numerals
2
and
3
a pair of output electrodes of the photovoltaic element, which are provided on the non-light receiving face side as shown in FIG.
3
(
d
).
In the inside of the photovoltaic element, there is provided a photoelectric conversion semiconductor layer having a plurality of p-n junction structures formed by alternately stacking a p-type semiconductor layer and an n-type semiconductor layer as shown in
FIG. 4
, where a p-type layer electrode
41
is electrically connected to each p-type semiconductor layer, and an n-type layer electrode
42
is electrically connected to each n-type semiconductor layer. The p-type electrode layers
41
are electrically connected to one of the two output electrodes
2
and
3
of the photovoltaic element and the n-type electrode layers
42
are electrically connected to the other output electrode of the photovoltaic element.
FIGS.
5
(
a
) to
5
(
d
) are schematic views illustrating the structure of an example of an optical-concentration type solar cell comprising a single crystal silicon material and in which light convergence is performed by means of a Fresnel lens.
Particularly, FIG.
5
(
a
) is a schematic plane view illustrating an appearance of a light receiving face side (the light receiving face having a reflection preventive film
51
) of the optical-concentration type solar cell, FIG.
5
(
b
) is a schematic view illustrating an appearance of a first side face of the optical-concentration type solar cell, FIG.
5
(
c
) is a schematic view illustrating an appearance of a second side face of the optical-concentration type solar cell, a
Kataoka Ichiro
Takeyama Yoshifumi
Yamada Satoru
Canon Kabushiki Kaisha
Wilson Allan R.
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