JP3222937B2 - Charge transfer type multiplier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transfer type multiplier using a semiconductor.

[0002]

2. Description of the Related Art CCDs and PCDs are known as elements for sequentially transferring electric charges. However, they do not have a multiplication mechanism. Also, taking a prior example focusing on electron multiplication, the electron multiplier is the closest in operation. Although the electron multiplier can perform electron multiplication while suppressing generation of noise, it can perform high S / N electron multiplication. However, since it is a vacuum tube, it has a large shape and is difficult to handle. The present invention has been made to solve these problems, and it is an object of the present invention to provide a charge transfer type multiplier having a completely new principle.

[0003]

According to the present invention, there is provided a charge transfer type multiplication device comprising: a plurality of electrodes provided on a semi-insulating semiconductor having a carrier concentration of 10 ¹² cm ^-3 or less; Means for applying an electric field of 0.5 kV / cm or more.

[0004]

The present invention relates to an apparatus for performing multiplication while moving electrons spatially, and provides a device having the same function as an electron multiplier as a semiconductor device. That is, when a plurality of electrodes are provided on a semi-insulating semiconductor and an electric field of 0.5 kV / cm or more is applied to the semi-insulating semiconductor therebetween, the electron scattering relaxation time τ _s is greatly reduced to about 70 picoseconds. And the mean free path increases accordingly. Also, the electric field concentrates on the anode part. By these two actions, avalanche multiplication can be realized even at a low electric field in the anode section. This has been clarified by the research of the present inventor. In the present invention, by connecting this electron multiplying mechanism in a cascade, carriers are transferred or multiplied while moving spatially.

[0005]

The present invention will be described with reference to specific examples.

FIG. 1 is a perspective view showing the structure of the apparatus of the embodiment. Electrodes 2 _i ( _i = 1 to ₁₎ on semi-insulating GaAs substrate 11
5) is provided, for voltage divider via a series resistor 3 _i resistor 4 _i
Is applied so as to apply a constant voltage divided by. Although FIG. 1 shows a structure in which charges are transferred in a zigzag manner using the front and back surfaces of a semiconductor thin plate for simplification, it is needless to say that electrodes can be arranged only on one side and transferred sequentially. Also, limit or an equivalent current path and the like put a score in the middle portion of the electrode 2 _i, it is possible to reduce an invalid current along the surface. That is, the semiconductor 1 ₁ and the electrode 2 ₁ arrangement has only to be sequentially potential therebetween there is sequentially homologous electrodes allocation, details of the structure is arbitrary. In particular, in this case, by selecting the distance between the electrodes 2 _i to be equal to or less than the mean free path, carriers can be accelerated and transferred to the next electrode.

[0007] Note that the semi-insulating substrate 1 ₁ surface, the electrodes 2 ₀ input terminal, electrode 2 ₆ of the electron for (multiplied electrons) Output
Are formed. The power supply 5 ₀ is connected to the electrode 2 _0, electrode 2 ₆ is connected to the output terminal OUT.
It should be noted that these electrodes 2 _0, 2 ₆ are bonded ohmic a semi-insulating substrate 1 _1.

With such an arrangement, avalanche multiplication is likely to occur between the electrodes 2 _i , but the situation is different if an avalanche occurs at one location. Potential drop due to the multiplication current, for lowering the potential of the adjacent electrode by a common impedance, the discharge electrode (avalanche electrode) is limited to the normal one, this time, the adjacent electrodes by applying a shift pulse to the terminal 6 _i When discharging is performed, the other electrodes are suppressed, and thus the on-electrode (discharge electrode) can be changed by the shift pulse. However, each electrode 2
_{When the} operating bias point at _i is excessively in the saturation region, it can be said that it does not have a function of sequentially multiplying, but rather constitutes a shift register, so that it can be used as a delay line (temporary storage) element. .

The electric field applied to each stage can be taken out without saturating the current by setting it lower than the turnover electric field to such an extent that avalanche multiplication occurs only by the current injected into each stage. The threshold electric field, when the semiconductor substrate 1 ₁ is a semi-insulating GaAs, from 0.5 2
It is about kV / cm. At this time, the signal input may be a carrier electrically injected into the first stage of the multiplication stage, and an appropriate input such as a means for generating the carrier by light irradiation, radiation irradiation, or the like can be considered. The signal output is taken out from the electrode _{26 at the} last stage as an electrical output.

A particularly excellent secondary electron multiplication type transfer apparatus is an apparatus that utilizes the Auger effect. Electrode 2 _i
By selecting a material that has a high Auger effect,
A device that transfers electrons by multiplying electrons by emitting secondary electrons can be realized. As described above, in a high resistance semiconductor, scattering of electrons is extremely small in a region where the electric field intensity is several kV / cm, and electrons can easily have high energy. Therefore, the electrons accelerated between the electrodes reach the anode in a state of high energy and strike the electrodes. When the electrode is made of a material having a high Auger effect, secondary electrons are emitted, further transmitted to the next stage and accelerated, and
The next electron is emitted. Examples of such an electrode having a high Auger effect include GaSb for a GaAs substrate and InSb and InAs for an InP substrate.

The biggest feature of the Auger electron multiplier is that
It is only electrons that are involved in secondary electron emission. That is, since only electrons are accelerated without being scattered, secondary electron emission can be easily performed. Thus, it is an ideal state from the viewpoint of S / N that only the electrons are multiplied by electrons, and the multiplication can be performed while keeping the S / N extremely high.

[0012]

According to the present invention, it is possible to perform the same function in a semiconductor as an electron multiplier which has been conventionally realized only with a vacuum tube. By utilizing the photoelectric conversion characteristics of the semiconductor, the photomultiplier can be used. The same effect can be achieved. In other words, the photomultiplier tube, which is inconvenient to handle due to the vacuum tube, and whose limit wavelength is limited due to vacuum radiation, can be realized in an easy-to-handle semiconductor, and the wavelength range can be greatly improved. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of the present invention.

[Description of Signs] 1 ₁ : High-resistance semiconductor, 2 ₁ : Electric station, 3 _i : Series resistance,
_i : Voltage dividing resistor, 5 _i : Power supply, 6 _i : Shift pulse input.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Iida, 1126 Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Inside (72) Inventor Yoshihisa Hoshina 1126, Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Hamamatsu Photonics Co., Ltd. (72) Inventor Kenichi Sugimoto 1126, Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Inside (72) Inventor Tomoko Suzuki 1126, Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Inside Hamamatsu Photonics Corporation (58) Field (Int.Cl. ⁷ , DB name) H01L 29/762-29/768

Claims (5)

(57) [Claims] An electric field of 0.5 kV / cm or more is sequentially applied between a plurality of electrodes provided on a semi-insulating semiconductor having a carrier concentration of 10 ¹² cm ^-3 or less and adjacent electrodes of the plurality of electrodes. Means, and said electrode is made of a material having a charge multiplication characteristic. 2. The charge transfer type multiplier according to claim 1, wherein an interval between said electrodes is set to be equal to or less than a mean free path of carriers. 3. The semiconductor device according to claim 1, wherein said semi-insulating semiconductor is semi-insulating GaAs.
The charge transfer type multiplier according to claim 1, wherein the charge transfer multiplier is s or semi-insulating InP. 4. The charge transfer type multiplier according to claim 1, wherein said electrode emits Auger electrons. 5. The method according to claim 1, wherein the electrode is GaSb, InAs or I
5. The charge transfer type multiplier according to claim 4, wherein the main material is a III-V semiconductor composed of any one of nSb and nSb.