JPS6042898B2 - Radiation wave detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention raises the temperature of a semiconductor device by irradiating optical power onto a semiconductor device including a Schottky electrode and a radiation wave absorbing film provided in contact with the vicinity of the Schottky electrode. Furthermore, the present invention relates to an optical power meter that detects a change in a reverse current flowing through a Schottky electrode caused by a rise in temperature and, as a result, measures the magnitude of the irradiated optical power.

Furthermore, the present invention aims to measure with high precision minute optical power of 1 μW or less obtained through semiconductor lasers and various spectrometers, which are currently becoming increasingly necessary.
As a method for detecting optical power, generally a photon type photodetector and a thermal type photodetector are used.

Examples of photon type photodetectors include photomultiplier tubes that utilize secondary electron emission due to light irradiation and photodiodes that utilize photoelectric effects. All of these devices utilize the quantum effect of light and have a high spectral sensitivity [cmH2+/W] and high-speed response, but on the other hand, they are highly dependent on wavelength and are difficult to use in the infrared region. When used, it has a lack of color and must be cooled to a low temperature before use. On the other hand, thermal photodetectors using a thermistor or bolometer have the advantage of having constant spectral sensitivity over the entire wavelength range (~40 μm) and being usable at room temperature. It has drawbacks such as being about 2 P smaller than a photon type photodetector and having a slow response speed. Possible causes of low spectral sensitivity include the large heat capacity of the photothermal conversion section and the generally small thermoelectric capacity of thermocouples.
Currently, various methods are being attempted to reduce the heat capacity including the light receiving surface. For example, published patent publication No. 53-13
There are 2282. However, these seem to have little practical advantage because of their weak mechanical strength and complicated manufacturing process. In view of the above points, the present invention focuses on the fact that the reverse current of a Schottky diode changes significantly depending on the temperature of the semiconductor, and uses a Schottky electrode and a radiation wave absorbing device provided in contact with the Schottky electrode. The radiation wave absorbing film of the semiconductor device equipped with the film absorbs the power of the irradiated light to increase the temperature of the semiconductor device, and the resulting change in the reverse current flowing through the Schottky electrode is expressed as the voltage across the DC bias impedance terminals. By detecting it as a fluctuation, it is intended to measure the magnitude of minute optical power of 1 μW or less with high precision.

For example, the operating impedance of a Schottky diode made of n-type GaAs with a donor electron concentration of 1016 per cubic centimeter as the semiconductor material and chromium as the Schottky electrode metal is reverse biased by approximately 6μ. When a constant voltage is reverse biased using a DC bias impedance with a magnitude of 1110, once the temperature of the semiconductor rises, the voltage fluctuation of the DC bias impedance becomes quite large, about 60 mV.

If the irradiated light power is absorbed by the radiation absorption film and heat is generated, it is possible to raise the temperature near the Schottky electrode by 0.1 degree or more even with a minute light power of 1 μW or less, so the above method is possible. using 1μ. It is possible to measure minute optical power of less than W with high precision. Figures 1 and 2
The figures show one embodiment of the present invention, in which FIG. 1 is a cross-sectional view of a semiconductor device 1 used in a detection section, and FIG. 2 is a cross-sectional view of a semiconductor device 1 used in a detection section. Shows how to configure it.

A semiconductor device 1 shown in FIG. 1 includes a semi-insulating semiconductor substrate 2, a semiconductor region 3 provided on the substrate, an ohmic electrode 4 and a Schottky electrode 5 provided on the semiconductor region 3, and a semiconductor device 1 shown in FIG. It is composed of a radiation wave absorbing film 6 provided near and in contact with a Schottky electrode 5, and is loaded on a mounting device. As the radiation wave absorbing film 6, a black body made of carbon black, gold black, pigment, dye, etc. is used. FIG. 2 is a diagram showing a method of configuring an optical power meter, in which a Schottky electrode 5 has a DC power supply 7, a DC bias impedance 8
A reverse bias is applied using

When the radiation wave absorbing film 6 is irradiated with optical power L, the optical power L is absorbed by the radiation wave absorbing film 6 and converted into heat. The heat generated in the radiation wave absorbing film 6 raises the temperature of the radiation wave absorbing film 6 itself, and also raises the temperature of the semiconductor region 3 due to the heat conduction effect. As a result, the reverse current flowing through the Schottky electrode 5 increases, and the voltage Vz between the DC bias impedance terminals increases. By amplifying the change in the voltage Vz between the DC bias impedance terminals at this time using the amplifier 9 and reading it with the meter 10, the magnitude of the irradiated optical power L can be measured. In this case, the reverse current flowing through the Schottky electrode 5 is greatly affected by the ambient temperature, and a so-called zero point drift occurs, so a temperature compensation circuit is required. Also, DC power supply 7
Since the reverse current flowing through the Schottky electrode 5 is greatly affected by voltage fluctuations, a highly stable DC power source is required. A method to solve the above problems is to construct a pair of Schottky diodes that exhibit almost the same characteristics, and to absorb optical power by providing a radiation wave absorbing film in close contact with one Schottky electrode. , the other Schottky electrode has a structure in which no radiation absorption film is provided. In this way, it is sufficient to adopt a structure that detects the difference in the magnitude of the reverse current flowing through both Schottky electrodes. explain.
3, 4 and 5 are a plan view of a semiconductor device 11 showing another embodiment of the present invention having the function of compensating for the above-mentioned zero point drift, and lines X-X'' and Y. -Y
''.A semiconductor device 11 described in this embodiment includes a semi-insulating semiconductor substrate 12 partially having a reverse recess structure, and a first semiconductor substrate 12 provided on the substrate corresponding to the position of the reverse recess. a semiconductor region 13 , and a semiconductor region 13 .
a first ohmic electrode 14 and a first Schottky electrode 15 provided on the Schottky electrode; a radiation wave absorbing film 16 provided in contact with the vicinity of the Schottky electrode; A second plate provided on the substrate 12
, a second ohmic electrode 18 and a second Schottky electrode 19 provided in the semiconductor region 17. It is used by being loaded onto these mounting devices. In this connection, the first Schottky electrode 1
At the same time, the heat generated in the radiation wave absorbing film 16 provided in contact with the vicinity of 5 increases the temperature of the first semiconductor region 13.
The heat is transmitted to the second semiconductor region 17 through the semi-insulating semiconductor substrate 12 with high thermal conductivity (the thermal conductivity of a normal semiconductor is around 1 watt/C77!K), and the second semiconductor region 1
In order to prevent the temperature of the second semiconductor region 17 from increasing, the back side of the semi-insulating semiconductor substrate 12 corresponding to the first semiconductor region 13 is formed into a thin structure, a so-called reverse concave structure, and conversely, the temperature of the second semiconductor region 17 is increased. If the semi-insulating semiconductor substrate 12 has a thick structure (approximately 200 μm) in order to make the temperature approximately equal to the ambient temperature, the distance between the first semiconductor region 13 and the second semiconductor region 17 may be as close as 500 pm. , second semiconductor region 17
This can eliminate the influence of heat generation in the radiation wave absorbing film 16 provided on and in contact with the Schottky electrode 15 in the first semiconductor region 13 .

In this case, the shape of the reverse concave portion can be either a pot shape or a pyramid trapezoid shape depending on the etching method, but the shape may be any shape as long as the heat suppression effect is taken into consideration. FIG. 6 is a diagram showing a method of configuring an optical power meter that measures the irradiated optical power L using the semiconductor device 11 loaded on a mounting device.

Each Schottky electrode 15, 19 of the semiconductor device 11 loaded on the mounting device is reverse biased using a DC power supply 20 and each DC bias impedance 21.
The irradiated light power L absorbed by the radiation wave absorbing film 16 is converted into heat, and the temperature of the first semiconductor region 13 increases due to heat conduction, so the reverse current flowing through the first Schottky electrode 15 increases. , the voltage between the DC bias impedance terminals becomes larger.

On the other hand, since the temperature of the second semiconductor region 17 is maintained approximately equal to the ambient temperature, the second Schottky electrode 1
9 is constant, and as a result, the voltage between the DC bias impedance terminals ``'' does not change. Therefore, the difference between the voltage value V and the voltage value V'' is absorbed by the radiation wave absorbing film 16. Since it is approximately proportional to the magnitude of the optical power L, if the voltage difference V-V'' is amplified using, for example, the amplifier 22 and read with the meter 23, the magnitude of the optical power L absorbed by the radiation wave absorption film 16 can be determined. This optical power meter configured using the semiconductor device 11 has a voltage difference V-■'' that is proportional to the irradiated optical power L and is not affected by changes in ambient temperature, so the so-called Zero point drift does not occur.

Furthermore, since the same DC power supply 20 is used to apply reverse bias to each Schottky electrode 15, 19, the influence of voltage fluctuations of the DC power supply can also be reduced. The semiconductor devices 1 and 11 used in each of the embodiments described above can be manufactured relatively easily using well-known photolithography and metal vacuum deposition methods.

An example in which gold black is used as the radiation absorbing film is obtained by introducing an inert gas into a high-vacuum bell jar and depositing gold in a low-vacuum state.

To make a part of the semi-insulating semiconductor substrate 12 thinner, that is, to create a reverse recess, after depositing a thin oxide film (SiO2 film),
This is done using photolithography. Next, the effects of the present invention will be described.

(1) Minute optical power of 1 μW or less, which has been difficult to measure in the past, can be measured at room temperature over a wide wavelength band (up to about 40 μm).

(2) Since the semiconductor device is easy to manufacture, it can be manufactured at a lower cost than conventional devices.

(3) No temperature compensation circuit is required.

As described above, the optical power meter according to the present invention has many advantages over conventional optical power meters.

Brief Description of the Drawings Figures 1 and 2 are diagrams showing embodiments of the present invention, Figure 1 is a cross-sectional view of a semiconductor device, and Figure 2 shows optical power using the semiconductor device shown in Figure 1. Figures 3, 4, 5 and 6 showing the configuration of the meter are diagrams showing other embodiments, and Figure 3 is a plan view of the semiconductor device, and Figures 4 and 5 are
The figures are cross-sectional views taken along lines X-X'' and Y''-Y'' in Figure 3,
FIG. 6 is a diagram showing the configuration of an optical power meter using the semiconductor device shown in FIG. 3.

In the drawing, 1 and 11 are semiconductor devices, 2 and 12 are semi-insulating semiconductor substrates, 3, 13, and 17 are semiconductor regions, and 4 and 14 are semiconductor devices.
, 18 are each ohmic electrode 5, 15, 19 are each Schottky electrode, 6, 16 are each radiation wave absorbing film, 7, 20 are DC power supplies, 8, 21 are each DC bias impedance, 9,
22 is each amplifier, and 10 and 23 are each meter.

Claims (1)

[Claims] 1. A semi-insulating semiconductor substrate, a semiconductor region formed on the substrate, an ohmic electrode and a Schottky electrode provided in the semiconductor region, and a method for transmitting radiation waves onto the vicinity of the Schottky electrode. a semiconductor device comprising: a radiation wave absorbing film for converting into heat; means for supplying a reverse bias to the Schottky electrode; a radiation wave detection device comprising: detection means for detecting a change in a reverse direction current flowing through the Schottky electrode due to a temperature rise caused by the temperature increase; 2. A semi-insulating semiconductor substrate with a portion having a reverse concave structure, and a first semiconductor region configured at a concave position on the substrate;
a first ohmic electrode and a first Schottky electrode provided in the semiconductor region; a radiation wave absorbing film provided near the Schottky electrode for converting radiation waves into heat; a second semiconductor region configured at a position outside the recess and having substantially the same characteristics as the semiconductor region; a second ohmic electrode and a second Schottky electrode configured in the second semiconductor region; a semiconductor device comprising; means for supplying a reverse bias to each of the Schottky electrodes; A radiation wave detection device comprising: means for detecting a difference in reverse current flowing through the first and second Schottky electrodes generated by the radiated wave detection device.