JP2597550B2 - Photoelectron beam conversion element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoelectron beam conversion device, and more particularly to a photoelectron beam conversion device using a solid-state electron beam generator.

[Conventional technology]

2. Description of the Related Art As a solid-state electron beam generator, there has been known an apparatus that applies an electric field to a heterogeneous junction formed in a semiconductor to emit an electron beam from a semiconductor surface to the outside.

For example, Japanese Patent Publication No. 54-30274 discloses a device in which a forward voltage is applied to an np junction formed of a mixed crystal of AlP and GaP to emit electrons from the surface of a P-type region. Japanese Patent Application Laid-Open No. 54-111272 discloses that a reverse voltage is applied to a pn junction at least partially exposed in an opening provided in an insulating layer on a semiconductor surface, and the insulating layer is accelerated to the edge of the opening. A solid-state electron beam generator provided with electrodes is disclosed in
No. 529 discloses that an acceleration electrode is provided at an edge of an opening provided in an insulating layer on a semiconductor surface, and a reverse voltage is applied to a pn junction extending parallel to the semiconductor surface in the opening to apply a reverse voltage to the semiconductor. A semiconductor device that emits electrons is disclosed in Japanese Patent Application Laid-Open Nos. 54-111272 and 56-15529, each of which discloses an electron beam generator integrated on a semiconductor substrate. Also, JP-A-57-38528 discloses that
There is disclosed a multi-cold electron emission cathode in which an element for emitting electrons from a semiconductor surface by applying a forward bias voltage to a pn junction is integrated on a semiconductor substrate.

These solid-state electron beam generators are compact and have p-
There are many advantages, such as that electron emission can be modulated by the voltage applied to the n-junction. Taking advantage of the advantage of miniaturization, a device in which a plurality of electron beams are arranged is conceivable. However, wiring for driving the electron beam generating device is complicated, which has been a problem.

On the other hand, DJBarteling, JLMoll, NIMeyer et al.
130. Number 3 (1963) 972-985, p-
It is reported that when a reverse voltage is applied to an n-junction to cause avalanche and generate electrons, the P-type region can be irradiated with light to excite and drive the electrons. But,
Excitation light is incident from the electron beam emission side, and this point has been a great limitation when used as a photoelectron beam conversion element.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photoelectron beam conversion element capable of generating an electron beam with a simple structure by eliminating the above-mentioned drawbacks of the conventional example and by applying light and applying a reverse voltage to a pn junction. And

[Means for solving the problem]

In order to achieve such an object, a photoelectron beam conversion element according to the present invention includes a semiconductor substrate, a plurality of p-type semiconductor regions formed on the substrate, and a plurality of p-type semiconductor regions provided on the plurality of p-type semiconductor regions. An n-type semiconductor region having an electron emission surface, a plurality of pn junctions formed by the plurality of p-type semiconductor regions and the plurality of n-type semiconductor regions, and an opposite side of the semiconductor substrate to the electron emission surface. An opening for light incidence formed toward the p-type semiconductor region at a position corresponding to each of the plurality of pn junctions from a surface; and the p-type semiconductor provided on the side having the opening. A common transparent electrode electrically connected to the region, a common electrode provided on the side having the electron emission surface and electrically connected to the n-type semiconductor region, and the plurality of common electrodes via the transparent electrode and the common electrode. Pn junction And having a means for applying a low reverse bias voltage than the breakdown voltage due to the child avalanche.

(Operation)

In the present invention, light is incident from an opening provided on the substrate side, and an electron beam is generated by applying a reverse voltage to the pn junction, whereby an electron beam can be easily generated by an optical signal.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a structure of a unit element constituting a first embodiment of the present invention. In FIG.
1 is a p-type Si substrate, 2 is a heavily doped p-type region, 3 is an n-type region, 4 is a pn junction, 5 is a work function lowering material such as a cesium (Cs) thin film, etc., 6 Is an insulating layer such as silicon oxide (Sio ₂ ), etc., 7 is an electron accelerating electrode, 8 is an electrode, 9 is an opening provided on the substrate side of a highly doped p-type region, and 10 is an SnO ₂ , ITO, etc. Transparent electrode. Such a device can be manufactured by a usual semiconductor lithography technique.

Next, the operation principle of the device of the present invention will be described. In this element, a reverse bias is applied to the pn junction by the drive circuit DC. This applied voltage is set slightly lower than a threshold electric field at which avalanche starts to occur. As shown in FIG. 1, the light L incident from the opening 9 on the back side of the high-concentration p-type region 2 passes through the transparent electrode 10 and
Excites electrons. The excited electrons serve as a trigger to cause avalanche of electrons, pass through the n-type region 3, and are accelerated by an electric field generated by the acceleration electrode 7 to emit an electron beam EB. A material that lowers the work function such as cesium is deposited on the surface of the n-type region 3 and can also emit low-energy electrons.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that the p-type Si
The operation principle is the same as that of the first embodiment except that the substrate 1 is etched to the high concentration p-type region 2. In the case of the second embodiment, the light L, which triggers the generation of the electron beam, directly hits the high-concentration p-type region 2 to increase the efficiency of the electron beam generation and further reduce the reverse bias electrode interval. There are advantages such as small size.

As a method of etching up to the high-concentration p-type region of the substrate 1, there are a method of performing wet etching with a mixture of hydrofluoric acid and nitric acid through a mask and a method of performing reactive ion etching using Cl ₂ gas. Since the distance between the substrates is as thick as about 500 μm, if the etching is not completed with one mask, the mask formation and etching may be repeated several times.

It is clear that a compound semiconductor can be used instead of Si in the first and second embodiments described above.

The elements shown in FIGS. 1 and 2 have a simple structure, and a plurality of elements can be integrated on a single substrate.

An embodiment of the present invention in which a plurality of unit elements shown as the first and second embodiments are integrated will be described with reference to FIG. In this embodiment, a plurality of the above-described unit elements are arranged (MEBS). Conventionally, when a plurality of photoelectron beam conversion elements are integrated and each of them is driven independently, wiring to each element becomes complicated, and this has been a cause of the high integration. In the case of this element, a plurality of photoelectron beam conversion elements MEBS are provided with a common transparent electrode 10 on the light input side,
On the other hand, only the common electrode 8 is provided in the n-type region on the electron beam emission side. 911, 912… 921, 922…, 955
Are openings corresponding to the electron beam sources, respectively. A reverse voltage slightly smaller than a voltage causing an avalanche of electrons is applied between the common transparent electrode 10 and the common electrode 8, and each electron beam is emitted to the opening on the substrate side corresponding to the electron beam source. It occurs when light is input.
As shown in FIG. 3, the electron beam EB11 is emitted from the electron beam generating element on which the light L11 is incident, and the electron beam EBmn is emitted similarly to the light Lmn.

[Effects of the Invention] As described above, in an apparatus that generates an electron avalanche and generates an electron beam, an opening is provided on the substrate side, light is incident, and a reverse voltage is applied to the pn junction. By generating an electron beam by doing
There is an effect that an electron beam can be easily generated by an optical signal. The photoelectron beam conversion device of the present invention can be applied to an optical exchanger and the like. Further, by adopting the configuration of the present invention, the electric wiring as the electron beam generator can be extremely simplified.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a sectional structure of a first embodiment of a unit element constituting the present invention, and FIG. 2 is a schematic view showing a sectional structure of a second embodiment of a unit element constituting the present invention. FIG. 3 is a schematic diagram showing a configuration of an embodiment of the present invention in which a plurality of unit elements shown in FIGS. 1 and 2 are arranged and formed. L, L1, LN: light, EB, EB1, EBN: electron beam, 1: p-type Si substrate, 2: high-concentration p-type region, 3: ... n-type region, 4: pn junction 5, a film that lowers the work function, 6: an insulating layer, 7: an electrode for accelerating electrons, 8: an electrode, 9, 911, 912 --- 9mn ... an opening, 10: a transparent electrode , DC: Element drive circuit, MEBS: Multi-photoelectron beam conversion element.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobutoshi Mizusawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasuhiko Ishiwatari 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Jin Oda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-50-23168 (JP, A) JP-A-62-299089 (JP) , A)

Claims (2)

(57) [Claims] A semiconductor substrate, a plurality of p-type semiconductor regions formed on the substrate, and an n-type semiconductor region provided on the plurality of p-type semiconductor regions, each having an electron emission surface.
A plurality of p-n junctions formed by the plurality of p-type semiconductor regions and a plurality of n-type semiconductor regions; and a plurality of p-n junctions from a surface of the semiconductor substrate opposite to the electron emission surface.
A light incident opening formed toward the p-type semiconductor region at a position corresponding to each of the n-junctions, and a common hole provided on the side having the opening and electrically connected to the p-type semiconductor region. A common electrode provided on the side having the electron emission surface and electrically connected to the n-type semiconductor region, and electron avalanche to the plurality of pn junctions via the transparent electrode and the common electrode. Means for applying a reverse bias voltage lower than the breakdown voltage caused by the photoelectron beam. 2. A photoelectron beam conversion device according to claim 1, wherein said electron emission surface has a film made of a work function lowering material.