JP3942296B2 - Multiple quantum well infrared sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multiple quantum well infrared sensor that receives infrared rays to acquire various information.
[0002]
[Prior art]
Systems that receive infrared rays emitted from a target, generate an infrared image, and acquire various types of information about the target are widely used. For example, in exploration of the earth's underground resources, the distribution of infrared rays radiated from the earth is observed by an infrared sensor mounted on an artificial satellite, and exploration of oil and mineral veins is performed.
[0003]
Among infrared sensors, a multiple quantum well infrared photosensor (QWIP) can change the excitation level of electrons by changing the width of the quantum well, so that the detection wavelength range can be controlled. it can. Therefore, if information of a plurality of detection wavelength regions is acquired by a multiple quantum well infrared light sensor having a plurality of detection wavelength regions, higher-order information can be obtained, and an infrared sensor for weapon guidance or defense can be obtained. Applications to fields that require more detailed information such as systems can be expected.
[0004]
FIG. 1 is a schematic configuration diagram of a conventional multiple quantum well infrared light sensor having two detection wavelength ranges. In this multiple quantum well infrared light sensor, a common electrode 14 is provided on a substrate 11 made of GaAs or the like, and a long wavelength infrared (LWIR) having a wavelength of about 8 to 10 μm is detected on the common electrode 14. The multiple quantum well layer MQW (Multi Quantum Well) 1 is provided. Next, on the first multiple quantum well layer MQW1, a second multiple quantum well layer MQW2 for detecting mid-wavelength infrared (MWIR) having a wavelength of about 3 to 5 μm via the contact layer 15 is provided. Provide. Then, the signal readout transistor T1 is connected to the contact layer 15, and the signal readout transistor T2 is connected to the electrode 16 on the second multiple quantum well layer MQW2.
[0005]
In the multi-quantum well infrared light sensor, when the infrared light in the detection wavelength region is received, electrons at the ground level are excited to the excitation level, and electrons that transition from the excitation level to the conduction band increase. When applied, current flows.
[0006]
In other words, when a bias voltage is applied to a multi-quantum well infrared light sensor, the current increases or decreases depending on the amount of infrared light received, so the amount of infrared light received can be measured by measuring the current value. Can do. In this case, the multiple quantum well infrared light sensor can be regarded as an impedance element whose value changes depending on the amount of received infrared light.
[0007]
Note that the impedance value of the multiple quantum well layer corresponds to the energy difference between the ground level and the excitation level. When this energy difference is small, the impedance is small, and when this energy difference is large, the impedance is also large. On the other hand, long-wavelength infrared has low energy, and the energy difference between the ground level and the excitation level of the multiple quantum well layer that absorbs long-wavelength infrared is small. In addition, medium wavelength infrared has a large energy, and the energy difference between the ground level and the excitation level of the multiple quantum well layer that absorbs the medium wavelength infrared is correspondingly large. For this reason, the impedance R1 of the first multiple quantum well layer MQW1 for detecting long-wavelength infrared (LWIR) is small, and the impedance R2 of the second multiple quantum well layer MQW2 for detecting medium-wavelength infrared (MWIR) is large, And the difference is very large,
R1 << R2
Is established.
[0008]
Accordingly, as shown in FIG. 1A, when the bias voltage V0 is applied from the common electrode 14, the transistor T1 is turned on and the transistor T2 is turned off, the bias voltage V0 is applied only to the first multiple quantum well layer MQW1. Then, long-wavelength infrared (LWIR) is detected (see FIG. 1 (2)).
[0009]
On the other hand, when the transistor T1 is turned off and the transistor T2 is turned on, most of the bias voltage is applied to the second multiple quantum well layer MQW2 having a large impedance R2 and applied to the first multiple quantum well layer MQW1 having a small impedance R1. Is hardly applied. In addition, the change in impedance due to the reception of infrared rays is dominated by the influence of the second multiple quantum well layer MQW2 having a large impedance R2, and only the reception of medium wavelength infrared rays (MWIR) can be detected.
[0010]
As described above, the conventional multiple quantum well infrared light sensor reads out signals corresponding to the two detection wavelengths in time series using the difference between the impedances R1 and R2 of the two multiple quantum well layers MQW1 and MQW1. It was.
[0011]
[Problems to be solved by the invention]
In the conventional multiple quantum well infrared light sensor, the impedance of the multiple quantum well layer is different by about two digits between the long wavelength infrared (LWIR) having a wavelength of about 8 to 10 μm and the medium wavelength infrared (MWIR) having a wavelength of about 3 to 5 μm. Each signal was read using the points.
[0012]
However, when a multiple quantum well layer having a detection wavelength of 8 to 9 μm and a multiple quantum well layer having a detection wavelength of 9 to 10 μm are stacked, the detection wavelength region is close and the difference in impedance between the multiple quantum well layers is reduced. For this reason, the signals of the two multiple quantum well layers are modulated with each other, the crosstalk between the two signals increases, and it becomes difficult to acquire information for each different wavelength.
[0013]
Therefore, the present invention can acquire signals from the respective detection wavelength ranges independently without causing crosstalk even when a plurality of detection wavelength ranges are close to each other, and the sum signal of each signal. It is another object of the present invention to provide a multiple quantum well infrared light sensor that can directly acquire a difference signal.
[0014]
[Means for Solving the Problems]
The above object is to provide a multiple quantum well infrared sensor in which a plurality of multiple quantum well layers each having sensitivity in different wavelength regions of infrared rays are stacked via a common contact layer, one end of which is connected to the common contact layer. Switch means and current integrating means connected to the other end of the switch means, and the first and second multiple quantum well layers on the opposite sides of the first and second multiple quantum well layers respectively formed above and below the common contact layer, First and second voltages are applied to the second contact layer, and one of the voltage between the common contact layer and the first contact layer and the voltage between the common contact layer and the second contact layer is made larger than the other. The switch means is turned on for a predetermined time, and the current integrating means is charged or discharged by a current flowing through the multiple quantum well layer. It is achieved by providing an optical sensor.
[0015]
According to the present invention, since the bias voltage can be individually applied to the multiple quantum well layers having different detection wavelength ranges by the electrode and the switch means, only the signal of the multiple quantum well layer to which the bias voltage is applied is crossed. It can be detected without talk.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.
[0017]
FIG. 2 is a principle configuration diagram and an equivalent circuit of a multiple quantum well infrared light sensor having two detection wavelength bands according to the present embodiment. The multiple quantum well infrared sensor of the present embodiment is provided with a first electrode (first contact layer) 17 on a substrate 11 such as GaAs, and a long wavelength having a wavelength of about 8 to 10 μm. A first multiple quantum well layer MQW1 for detecting infrared rays (LWIR) is provided. Next, on the first multiple quantum well layer MQW1, a second multiple quantum well layer MQW2 that detects medium-wavelength infrared (MWIR) having a wavelength of about 3 to 5 μm is provided via the common contact layer 18. Then, a signal reading transistor T3 is connected to the common contact layer 18 as a switching means, and a second electrode (second contact layer) 19 is provided on the second multiple quantum well layer MQW2. The other end of the switch means T3 is connected to a capacitor Cint that integrates the current flowing through the multiple quantum well layers MQW1 and MQW2.
[0018]
As described above, the multiple quantum well layers MQW1 and MQW2 can be regarded as the resistors R1 and R2 that are modulated by the infrared input, and the multiple quantum well infrared sensor of FIG. It can be expressed by the equivalent circuit of 2).
[0019]
Next, the operation of the multiple quantum well infrared light sensor of the present embodiment will be described with reference to FIG. In the multi-quantum well infrared sensor of this embodiment, the capacitor Cint is charged in advance with a predetermined voltage, and the bias voltage V1 or V2 is applied to either the first electrode 17 or the second electrode 19. To do. In this state, a control voltage Vg is applied to the gate electrode of the transistor T3, and the transistor T3 is turned on for a predetermined time ΔT.
[0020]
The multiple quantum well layers MQW1 and MQW2 flow a current corresponding to the intensity of infrared rays in the detection wavelength range only when a bias voltage is applied, and discharge or charge the capacity charged in the capacitor Cint. When the voltage drop or rise of the capacitor Cint is measured, the intensity of infrared rays received by the multiple quantum well layer can be detected.
[0021]
In this case, a control voltage Vg close to the gate-source threshold voltage Vt of the transistor T3 is applied to the gate electrode of the transistor T3. The conductance of the transistor T3 is controlled to be sufficiently large (impedance is sufficiently small). Therefore, the voltage at the connection point N1 between the multiple quantum well layers MQW1 and MQW2 is a voltage that is lowered by the gate-source threshold voltage Vt from the control voltage Vg (≈Vt), that is, approximately 0 [V].
[0022]
Therefore, as shown in FIG. 2 (3) a, when V1 = −2 [V] is applied to the first electrode 17 and V2 = 0 [V] is applied to the second electrode 19, the multiple quantum well layer MQW1 is A discharge voltage I1 flows when a bias voltage of 2 [V] is applied, but almost no current flows because no bias voltage is applied to the multiple quantum well layer MQW2. On the other hand, when V2 = −2 [V] is applied to the second electrode 19 and V1 = 0 [V] is applied to the first electrode 17, as shown in FIG. 2 (3) b, the multiple quantum well layer MQW2 is applied. In FIG. 2, a bias voltage of 2 [V] is applied and a discharge current flows. However, almost no current flows because no bias voltage is applied to the multiple quantum well layer MQW1.
[0023]
The fact that the voltage at the connection point N1 between the multiple quantum well layers MQW1 and MQW2 is fixed in the vicinity of 0 [V] will be described with reference to the characteristic diagram. FIG. 3 is an explanatory diagram of operating points when a bias voltage V1 is applied to the multiple quantum well layer MQW1 (R1). When the source voltage Vs of the transistor T3 is taken on the horizontal axis and the current It flowing through the transistor T3 is taken on the vertical axis, the current It rises steeply like a characteristic curve 20 in a region where the source voltage Vs is (Vg−Vt) or less. . That is, the impedance of the transistor T3 is sufficiently small. Here, Vg and Vt are the gate voltage and threshold voltage of the transistor T3.
[0024]
Further, since the current I1 flowing through the multiple quantum well layer MQW1 is represented by the straight line 21 corresponding to the resistance value R1, the intersection point of the characteristic curve 20 and the straight line 21 (point of It = I1) becomes the operating point 22. Therefore, even if the bias voltage V1 changes to V1 ′ or R1 changes to R1 ′ and R1 ″ within a range where the impedance of the transistor T3 is sufficiently smaller than R1, the voltage Vs at the operating point 22 is 0 [V]. Fixed in the vicinity.
[0025]
FIG. 4 is an explanatory diagram of operating points when a bias voltage V1 is applied to the multiple quantum well layer MQW1 (R1) and a bias voltage V2 having a polarity opposite to V1 is applied to the multiple quantum well layer MQW2 (R2). The current I1 is represented by a straight line 25 corresponding to the resistance value R1, and the current I2 is represented by a straight line 26 corresponding to the resistance value R2. Since the current It obtained by subtracting the current I2 from the current I1 flows through the transistor T3, the operating point 22 in this case is an intersection of the characteristic curve 20 and the straight line 27. Therefore, in this case, the voltage Vs at the operating point 22 is fixed near 0 [V] under the condition of I1> I2.
[0026]
Thus, in the multiple quantum well infrared light sensor of the present embodiment, the voltage Vs at the operating point 22 is fixed in the vicinity of 0 [V], and the voltage V1 of the first and second electrodes of the multiple quantum well layer. By controlling V2 as shown in FIG. 2 (3), it is possible to individually apply a bias voltage to multiple quantum well layers having different detection wavelength ranges. Therefore, only the signal of the multiple quantum well layer to which the bias voltage is applied can be detected without crosstalk.
[0027]
FIG. 5 is a schematic diagram of a multi-quantum well infrared light sensor having four multi-quantum well layers. In this case, the first to fourth multiple quantum well layers MQW1, MQW2, MQW3, MQW4 having different detection wavelength ranges are stacked, and the electrode 30 that applies the voltage V3 to the upper end of the first multiple quantum well layer MQW1 is provided. The electrode 31 for applying the voltage V4 is provided at the connection point between the second and third multiple quantum well layers MQW2 and MQW3, and the electrode 32 for applying the voltage V5 is provided at the lower end of the fourth multiple quantum well layer MQW4. The transistor T4 is connected to the connection point N2 corresponding to the common contact layer of the first and second multiple quantum well layers MQW1 and MQW2, and the common contact layer of the third and fourth multiple quantum well layers MQW3 and MQW4 is connected. The transistor T5 is connected to the corresponding connection point N3.
[0028]
According to the multiple quantum well type infrared light sensor of this configuration, infrared rays in four different wavelength ranges can be individually detected without crosstalk. That is, when detecting the infrared ray IR1 in the detection wavelength region of the first multiple quantum well layer MQW1, as shown in FIG. 5 (2) a, V3 = −2 [V], V4 = V5 = 0 [V]. The transistor T4 is turned on and the transistor T5 is turned off. In this case, as described above, if the gate voltage Vg of the transistor T4 is made substantially equal to the threshold voltage Vt of the transistor T4, the voltage at the node N2 becomes substantially 0 [V], and only the signal of the multiple quantum well layer MQW1 is detected. can do.
[0029]
When detecting the infrared IR2 in the detection wavelength region of the second multiple quantum well layer MQW2, as shown in FIG. 5 (2) b, V4 = −2 [V], V3 = V5 = 0 [V], When the transistor T4 is turned on, the transistor T5 is turned off, and the infrared IR3 in the detection wavelength region of the third multiple quantum well layer MQW3 is detected, V4 = −2 [V], as shown in FIG. When V3 = V5 = 0 [V], the transistor T4 is OFF, the transistor T5 is ON, and the infrared IR4 in the detection wavelength region of the fourth multiple quantum well layer MQW4 is detected, as shown in FIG. V5 = −2 [V], V3 = V4 = 0 [V], the transistor T4 is turned off, and the transistor T5 is turned on.
[0030]
FIG. 6 is a configuration diagram of the unit cell 35 of the multiple quantum well infrared sensor according to the first embodiment of this invention. As in FIG. 2B, the multiple quantum well infrared sensor of the present embodiment is a first multiple quantum well layer MQW1 that detects infrared IR1, and a second multiple quantum well layer that detects infrared IR2. It has an MQW2, a signal reading transistor T3, and a capacitor Cint, and further includes a reset transistor T6 that precharges the capacitor Cint, and a source follower transistor T7 that extracts the charging voltage of the capacitor Cint with low impedance.
[0031]
When detecting infrared rays, first, a reset signal ΦR is input to the gate of the transistor T6 to turn on the transistor T6, and the capacitor Cint is precharged with a power source Vdd of, for example, 5 [V]. Then, as described above, a bias voltage is applied to the multiple quantum well layer MQW1 or MQW2 in the wavelength region that is detected by controlling the voltages V1 and V2.
[0032]
Next, the control voltage Vg is input to the gate of the transistor T3 to make the transistor T3 conductive for a predetermined time. As described above, the control voltage Vg is made substantially equal to the threshold voltage Vt between the gate and source of the transistor T3. Therefore, the connection point N1 between MQW1 and MQW2 is fixed at approximately 0 [V], and only the amount of current corresponding to the amount of infrared light received by the multiple quantum well layer to which the bias voltage is applied can be detected. Since the charge of the capacitor Cint is discharged by the current I1 or I2 flowing through the multiple quantum well layer to which a bias voltage is applied, the voltage Vc of the capacitor Cint becomes a voltage corresponding to the intensity of received infrared light after a predetermined time. . The voltage Vc is taken out from the source terminal of the source follower transistor T7 with low impedance.
[0033]
In FIG. 6, the output of the source follower transistor T7 is output via the transistors T10 and T11 selected by the horizontal scanning line W1 and the vertical scanning line W2, which will be described later.
[0034]
FIG. 7 is a configuration diagram of the unit cell 35 of the multiple quantum well infrared sensor according to the second embodiment of the present invention. The multiple quantum well infrared sensor of the present embodiment includes a first multiple quantum well layer MQW1 that detects infrared IR1, a second multiple quantum well layer MQW2 that detects infrared IR2, and a transistor that operates as a switch means. T13, and further includes a capacitor Cint for integrating the detected current, an operational amplifier OP1, and a reset transistor T14.
[0035]
In the multiple quantum well infrared sensor of the present embodiment, first, a reset signal ΦR is input to the gate of the transistor T14 to conduct it, and the charge of the capacitor Cint is discharged. Then, as described above, a bias voltage is applied only to the multiple quantum well layer in the wavelength region that is detected by controlling the voltages V1 and V2. Note that a reference voltage Vref≈0 [V] serving as a virtual ground is applied to the non-inverting input terminal (+) of the operational amplifier OP1.
[0036]
Next, the input signal Vin is input to the gate of the transistor T13, and the transistor T13 is turned on for a predetermined time. In this case, the transistor T13 operates as a switch, and the voltage drop is almost zero. Accordingly, the connection point N1 between MQW1 and MQW2 becomes equal to 0 [V] of the reference voltage Vref, and the capacitor Cint is charged or discharged so as to maintain the state. That is, the capacitor Cint is charged in the direction of the arrow 36 from the output terminal of the operational amplifier OP1 in accordance with the current flowing through the multiple quantum well layer to which the bias voltage is applied, so that the voltage of the capacitor Cint is The voltage corresponds to the intensity of the received infrared light. Therefore, it is possible to detect only the infrared light reception of the multiple quantum well layer to which the bias voltage is applied.
[0037]
FIG. 8 is a configuration diagram of a multiple quantum well infrared sensor according to a third embodiment of the present invention. FIG. 8A illustrates a unit cell 35 of the multiple quantum well infrared sensor configured in a one-dimensional array. FIG. 8B shows an example in which the unit cells 35 are configured in a two-dimensional array.
[0038]
The one-dimensional array in FIG. 8A uses, for example, the multi-quantum well infrared sensor of the second embodiment shown in FIG. Then, the signal voltage output from the unit cell 35 is output to the common bus line 45 via the switching transistor T20 sequentially driven by the shift register 40.
[0039]
The two-dimensional array in FIG. 8B uses, for example, the multiple quantum well infrared sensor of the first embodiment shown in FIG. 6 as the unit cells 35 arranged in four rows and four columns. Then, the signal voltage output from the unit cell 35 is output to the vertical bus line 46 via the switching transistor T 10 driven by the vertical shift register 43, and the signal of the vertical bus line 46 is driven by the horizontal shift register 44. Signal multiplexing is performed by outputting to the output bus line 47 via the switching transistor T11. The bias voltages V1 and V2 are supplied from the power sources 41 and 42, and the transistor T12 is a current source serving as a load.
[0040]
FIG. 9 is an explanatory diagram of a current subtraction circuit added to the multiple quantum well infrared sensor according to the embodiment of the present invention. In the multiple quantum well layers MQW1 and MQW2, detection currents I1 and I2 flow when infrared rays are received, but dark currents due to thermal excitation flow even when infrared rays are not received. Therefore, the multiple quantum well infrared sensor of the present embodiment adds a current subtraction circuit to cancel the offset due to dark current and increase the dynamic range of detection.
[0041]
FIG. 9 (1) is a principle configuration diagram of the current subtraction circuit of the present embodiment, and a current Is equal to the dark current is supplied from the current source 50 to the connection point N1 of the multiple quantum well layers MQW1 and MQW2. Accordingly, the signal current Iin flowing through the transistor T3 has a value obtained by subtracting the current Is from the sum of the currents I1 and I2, and the offset due to the dark current can be canceled from the signal current Iin.
[0042]
FIG. 9 (2) shows a current subtracting circuit constituted by a resistor, in which a resistor R connected to the power source Vs is connected to the node N1, and a current Is = Vs / R equal to the dark current is supplied. FIG. 9 (3) shows a current subtracting circuit constituted by MOS transistors, in which a p-type MOS transistor T21 connected to the power supply Vdd is connected to the node N1, and a dark current is supplied by the saturation current Is. It is.
[0043]
FIG. 9 (3) shows a current subtraction circuit composed of a switch and a capacitor. A switched capacitor circuit including switch transistors T22 and T23 and a capacitor Cs is connected to the node N1, and a current Is equal to the dark current is supplied. Is. That is, the switch transistor T22 is turned on by the timing signal Φs and charges the capacitor Cs with the current from the power source Vs. The switch transistor T23 is turned on by the inversion timing signal Φs / and supplies the discharge current from the capacitor Cs to the node N1. This discharge current Is is made equal to the dark current. When the frequency of the timing signal Φs is f, the charge charged in the capacitor Cs is Qs = Cs · Vs, and thus the discharge current Is = Cs · Vs · f.
[0044]
FIG. 10 is an explanatory diagram of a signal readout mode in the multiple quantum well infrared sensor of the present embodiment. In the present embodiment, by controlling the bias voltage of each multiple quantum well layer, the detection current of each multiple quantum well layer can be read individually without crosstalk, and the sum and difference of each detection current are also read directly. Therefore, the configuration of the multiple quantum well infrared sensor can be simplified.
[0045]
FIG. 10A shows a case where the current I1 of the multiple quantum well layer MQW1 is read, and the voltage V1 = −2 [V] is applied to the electrode 17 and 0 [V] is applied to the electrode 19. In this case, as described above, the node N1 is fixed to approximately 0 [V], and a bias voltage is applied only to the multiple quantum well layer MQW1, so that the current Iin = I1 flows through the transistor T3, and the multiple quantum well layer MQW1. Can only read out.
[0046]
FIG. 10B shows a case where the current I2 of the multiple quantum well layer MQW2 is read, and 0 [V] is applied to the electrode 17 and a voltage V2 = −2 [V] is applied to the electrode 19. In this case, the current Iin = I2 flows through the transistor T3, and only the multiple quantum well layer MQW2 can be read.
[0047]
FIG. 10 (3) shows a case where the sum of the current I1 of the multiple quantum well layer MQW1 and the current I2 of the multiple quantum well layer MQW2 is read. The voltage V1 = −2 [V] is applied to the electrode 17 and the voltage V2 is applied to the electrode 19. = -2 [V] is applied. Also in this case, since the voltage of the node N1 is fixed to approximately 0 [V], a bias voltage is applied to both the multiple quantum well layer MQW1 and the multiple quantum well layer MQW2, and a current Iin = I1 + I2 flows through the transistor T3. The sum signal of the multiple quantum well layer MQW1 and the multiple quantum well layer MQW2 can be read out.
[0048]
FIG. 10 (4) shows a case where the current difference between the current I1 of the multiple quantum well layer MQW1 and the current I2 of the multiple quantum well layer MQW2 is read, and the voltage V1 = −2 [V] at the electrode 17 and the voltage V2 at the electrode 19. = + 2 [V] is applied. Also in this case, since the voltage of the node N1 is fixed to approximately 0 [V], a bias voltage having a reverse polarity is applied to the multiple quantum well layer MQW1 and the multiple quantum well layer MQW2, and the current Iin = I1-I2 is applied to the transistor T3. The difference signal between the multiple quantum well layer MQW1 and the multiple quantum well layer MQW2 can be read out.
[0049]
FIG. 11 is an explanatory diagram showing an example of an embodiment of a multiple quantum well infrared sensor according to an embodiment of the present invention. In order to detect a distant target 51 as shown in FIG. 11 (1), the search is performed in the sum signal mode. In the sum signal mode, signals in two wavelength regions are added, so that a high S / N ratio can be realized, and the target 51 in the distance can be tracked.
[0050]
As shown in FIG. 11 (1), when the target 51 approaches and the signal intensity increases, the signals in the respective wavelength ranges are individually acquired, and the respective signals are compared to identify and classify the target 51 from the characteristics. It becomes possible to do. When the target 51 is further approached, the difference between the signals in the respective wavelength ranges can be detected by the difference signal mode, and the detailed structure of the target 51 can be recognized.
[0051]
【The invention's effect】
As described above, according to the present invention, even when a plurality of detection wavelength regions are close to each other, signals from each detection wavelength region can be read independently without causing crosstalk, and each The sum signal and difference signal of the signals can be read directly.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a conventional multiple quantum well infrared light sensor.
FIG. 2 is a principle configuration diagram and equivalent circuit of a multiple quantum well infrared light sensor of the present invention.
FIG. 3 is an explanatory diagram (I) of an operating point of the multiple quantum well infrared light sensor of the present invention.
FIG. 4 is an explanatory diagram (II) of an operating point of the multiple quantum well infrared sensor of the present invention.
FIG. 5 is a schematic view of a multi-quantum well infrared light sensor having a multilayer structure according to the present invention.
FIG. 6 is a configuration diagram of a multiple quantum well infrared sensor according to the first embodiment of the present invention.
FIG. 7 is a configuration diagram of a multiple quantum well infrared light sensor according to a second embodiment of the present invention.
FIG. 8 is a configuration diagram of a multiple quantum well infrared light sensor according to a third embodiment of the present invention.
FIG. 9 is an explanatory diagram of a current subtraction circuit in the embodiment of the present invention.
FIG. 10 is an explanatory diagram of a signal read mode in the embodiment of the present invention.
FIG. 11 is an explanatory diagram of an embodiment of a multiple quantum well infrared light sensor according to an embodiment of the present invention.
[Explanation of symbols]
MQW multiple quantum well layer
LWIR Long wavelength infrared
MWIR Mid-wavelength infrared
17, 19 electrodes
18 Contact layer
T3, T6, T7 transistors
Cint integration capacitor
35 unit cells
OP1 operational amplifier
43 Vertical shift register
44 Horizontal shift register

Claims (9)

In a multiple quantum well type infrared light sensor in which a plurality of multiple quantum well layers each having sensitivity in different wavelength regions of infrared are stacked via a common contact layer,
Switch means having one end connected to the common contact layer;
Current integrating means connected to the other end of the switch means;
First and second voltages are applied to first and second contact layers opposite to the first and second multiple quantum well layers respectively formed above and below the common contact layer, and the common contact layer and The switch means is made conductive for a predetermined time so that one of the voltage between the first contact layers and the voltage between the common contact layer and the second contact layer is larger than the other, and the current flowing in the multiple quantum well layer Charging or discharging the current integrating means ;
The multi-quantum well infrared sensor further comprises a current source for supplying a current substantially equal to a dark current of the multi-quantum well layer to the common contact layer to which the switch means is connected . In a multiple quantum well type infrared light sensor in which a plurality of multiple quantum well layers each having sensitivity in different wavelength regions of infrared are stacked via a common contact layer,
  Switch means having one end connected to the common contact layer;
  Current integrating means connected to the other end of the switch means;
  First and second voltages are applied to first and second contact layers opposite to the first and second multiple quantum well layers respectively formed above and below the common contact layer, and the common contact layer and The switch means is made to conduct for a predetermined time so that one of the voltage between the first contact layers and the voltage between the common contact layer and the second contact layer is larger than the other, and the current flowing in the multiple quantum well layer Charging or discharging the current integrating means;
Voltages having different polarities are applied to the first and second contact layers, and the current integrating means is charged or discharged with a current difference between currents flowing through the first and second multiple quantum well layers. A multiple quantum well infrared sensor. Oite to claim 1 or 2,
The first and second voltages are alternately applied in time series to the first and second contact layers, and the amount of current flowing in response to infrared rays in the different wavelength regions is detected via the current integrating means. A multi-quantum well infrared sensor characterized in that: In claim 1 or 2 ,
The multiple quantum well infrared light sensor, wherein the switch means has a larger conductance than the multiple quantum well layer. In claim 1 or 2 ,
The multi-quantum well infrared sensor, wherein the switch means is a transistor having a source connected to the common contact layer, a drain connected to the current integration means, and a control voltage applied to the gate. Oite to claim 5,
The current integrating means comprises a capacitor, the capacitor is reset to a predetermined voltage, and the voltage of the capacitor that changes according to the current flowing in the multiple quantum well layer is detected by a source follower transistor. Well type infrared light sensor. Oite to claim 5,
The multi-quantum well type wherein the current integrating means comprises a feedback capacitor of an operational amplifier, the feedback capacitor is discharge-reset, and an output voltage of the operational amplifier changes according to a current flowing through the multiple quantum well layer Infrared light sensor. In claim 1,
A voltage having the same polarity is applied to the first and second contact layers, and the current integrating means is charged or discharged with a sum of currents flowing through the first and second multiple quantum well layers. A multiple quantum well infrared sensor. Multi-quantum well infrared light sensor, characterized in that a multi-quantum well infrared sensor according to rows or a matrix to claim 1乃optimum 8.

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