CN1044531A - Photoelectric detector with internal modulation and indirect coupling - Google Patents

Abstract

The invention discloses a kind of indirect coupling photodetector of internal modulation, do not add under the situation of chopper, can be converted to constant weak light the photosignal of modulation, reach the purpose that improves signal to noise ratio (S/N ratio).Detector provided by the invention has advantages such as equipment is simple, cheap and easy to use.

Description

Photoelectric detector with internal modulation and indirect coupling

Novel photoelectric-detection device provided by the invention is the indirect coupling photodetector of another type.

In order to survey atomic weak light, on the path of light source and detector, put a chopper usually, a branch of constant light is chopped into the light modulated with fixed frequency, carry out photodetection and frequency-selecting then and amplify, so as to increasing substantially the signal to noise ratio (S/N ratio) of detection system.

Though said system can detect faint light, the equipment complexity, cost an arm and a leg, use also inconvenient.For example this method just is not suitable for field, family and other simple application.

The present invention is a method of utilizing coupled structure in the modulation indirect coupling photodetector, makes a kind of photodetector of internal modulation.When it receives a branch of constant weak light time, the photosignal output of modulation is arranged promptly.

Principle of the present invention is that example is described as follows with Figure 1A and Figure 1B.Add the voltage shown in Figure 1B between metal (15) and substrate (10), make passage (14) be in weak anti-type state and non-strong inversion, the output NP knot (12) under the reverse biased has only very little reverse saturation current to flow through.Under the illumination, be subjected to light PN junction (16) under the effect of open-circuit voltage, the electronics in N district will be by heat emission or diffusion and admission passage (14) transfers to output NP knot (12) to the right and is output the photosignal of output that Here it is along passage (14) then.If superpose the sinusoidal voltage of a small magnitude again on grid (15), the electromotive force in the passage (14) is modulated, then the electron stream density that flows to passage (16) with sinusoidal variations, output also will be the photosignal of sinusoidal variations.

Photoelectric detector with internal modulation and indirect coupling can have varied.For example substrate (10) can be the P type, can also be the N type; Being subjected to light knot (16) can be NP knot, PN junction, heterojunction or schottky junction.Being subjected to light knot (16), connecting between passage (14) and the follower (12), can be that monolithic is integrated, also can mix assembling.Connecting between passage (14) and the follower (12), can be monolithic integrated optical circuit.Passage (14) can use the field effect method of MIS, PN junction or schottky junction etc. to form.

Here Fa Ming internal modulation photodetector can provide the light modulated electric signal of faint light under the situation of no chopper.Both improved signal to noise ratio (S/N ratio), and simplified testing apparatus again significantly and made things convenient for application, the technology of surveying faint light had been pushed ahead major step.

Figure 1A is the vertical view that explanation photoelectric detector with internal modulation and indirect coupling principle exemplifies, and Figure 1B is the sectional view of Figure 1A along the 1-1 line.The 10th, P type silicon substrate, the 12nd, output NP knot, the 13rd, the output aluminum lead, the 14th, passage, the 15th, gate electrode, the 16th, tied by light NP.

Fig. 2 A is the vertical view of internal modulation indirect coupling silicon phototriode tube core.Fig. 2 B is the sectional view of Fig. 2 A along the 2-2 line.The 20th, N type silicon substrate, the 21st, the output triode launch site, the 22nd, the collector junction of output triode, the 23rd, output triode launch site aluminium electrode, the 24th, passage, the 25th, the metal alum gate, the 26th, be subjected to the light PN junction.

Inventive embodiments.

The technical scheme of making internal modulation indirect coupling phototriode is described as follows with reference to Fig. 2:

1, be that the N type silicon of 2-100 Ω cm is made substrate (20) material with resistivity;

2, conventional planar technology oxidized silicon chip, 6000 ° of oxidation bed thickness are more than the A;

3, photoetching is distinguished and the output triode base with the light PN junction (26) that is subjected to that passage (24) connects each other, and passage (24) length is 1-40 μ m;

4, boron diffusion forms and is subjected to light PN junction (26) and output triode collector junction (22), junction depth 3-4 μ m, and doping content is 5 * 10 ¹⁷～5 * 10 ¹⁸Cm ^-3;

5, photoetching triode launch site (21) carry out phosphorous diffusion then, and the amplification coefficient that makes triode is greater than 100;

6, following technology is identical with the common phototriode of making.

Claims (3)

1, photoelectric detector with internal modulation and indirect coupling, it is formed by light knot (16), passage (14) and output device (12) by open circuit.It is characterized in that said to be subjected to light knot (16) can be PN junction, NP knot, heterojunction or schottky junction, said passage (14) can use MIS, PN junction and schottky junction formation, and it only is in weak anti-type state, can also modulate with impressed voltage.

2, by the photodetector of claim 1 defined, it is characterized in that said passage (16) length is 1-40 μ m

3, by the photodetector of claim 1 and 2 defineds, it is characterized in that said output device (12) can be diode, triode or integrated circuit.

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