JPH05264339A - Photodetector - Google Patents
PhotodetectorInfo
- Publication number
- JPH05264339A JPH05264339A JP6044392A JP6044392A JPH05264339A JP H05264339 A JPH05264339 A JP H05264339A JP 6044392 A JP6044392 A JP 6044392A JP 6044392 A JP6044392 A JP 6044392A JP H05264339 A JPH05264339 A JP H05264339A
- Authority
- JP
- Japan
- Prior art keywords
- light
- light receiving
- receiving element
- wavelength
- reverse bias
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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Landscapes
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、特定の波長帯域の光を
検出する光検出器に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector for detecting light in a specific wavelength band.
【０００２】[0002]
【従来の技術】特定の波長帯域の光を検出するために
は、一般に、濾波特性の異なる光フィルタ若しくは分光
器または分光感度特性の異なる光検出素子を用いて構成
される。そのような光検出器の一例として図５に示すよ
うな構成のものがある。赤フィルタＦR ，青フィルタＦ
B を通過した光をＰＤ１，ＰＤ２で検出し、ＯＰアンプ
ＯＰ３でそれらの検出レベルの差からこれらのフィルタ
ＦR ，ＦB で与えられる特定の波長帯域の光を検出して
いる。2. Description of the Related Art In order to detect light in a specific wavelength band, generally, an optical filter or spectroscope having different filtering characteristics or a photodetecting element having different spectral sensitivity characteristics is used. An example of such a photodetector is one having a structure as shown in FIG. Red filter F R , blue filter F
The light passing through B is detected by PD1 and PD2, and the light of a specific wavelength band given by these filters F R and F B is detected by the OP amplifier OP3 from the difference in their detection levels.
【０００３】[0003]
【発明が解決しようとする課題】前述のような光検出器
では、光フィルタ若しくは分光器は高価なものであるた
めコストがかかるという問題がある。また、小型化する
には限界があり、フィルタや素子のバラツキを押さえる
ために抵抗などの定数をセットごとに調整しなければな
らない。さらに、応答速度については、より高速化する
ためにコンパレータを用いたとしてもせいぜいマイクロ
セカンドオーダである。このように、既存の汎用ＩＣを
用いて構成していることに起因する問題点があった。In the photodetector as described above, there is a problem that the optical filter or the spectroscope is expensive and therefore costly. Further, there is a limit to miniaturization, and constants such as resistances must be adjusted for each set in order to suppress variations in filters and elements. Further, the response speed is at most microsecond order even if a comparator is used for higher speed. As described above, there is a problem caused by the configuration using the existing general-purpose IC.
【０００４】[0004]
【課題を解決するための手段】上記課題を解決するため
に、本発明の光検出器は、逆バイアス電圧が小さくなる
とその吸収波長端が長波長側にシフトする第１の受光素
子と、第１の受光素子よりも短い吸収波長端を有すると
ともに逆バイアスの大きさに応じてその吸収波長端が長
波長側にシフトする第２の受光素子とを有し、第１及び
第２の受光素子を逆バイアスが印加されるように直列接
続するとともに被検出光が第１及び第２の受光素子の双
方に入射されるようにしたことを特徴とする。In order to solve the above-mentioned problems, the photodetector of the present invention comprises: a first light-receiving element whose absorption wavelength end is shifted to a long wavelength side when the reverse bias voltage becomes small; A second light receiving element having an absorption wavelength edge shorter than that of the first light receiving element and having its absorption wavelength edge shifted to the long wavelength side in accordance with the magnitude of the reverse bias. Are connected in series so that a reverse bias is applied, and the detected light is made incident on both the first and second light receiving elements.
【０００５】また、第１及び第２の受光素子が第１導電
層と、第２導電層と、第１導電層及び第２導電層の間に
設けられ、半導体超格子をなす多重量子井戸層とで構成
されていることを特徴としても良い。Further, the first and second light receiving elements are provided between the first conductive layer, the second conductive layer, and the first conductive layer and the second conductive layer, and a multiple quantum well layer forming a semiconductor superlattice is formed. It may be characterized by being composed of and.
【０００６】[0006]
【作用】本発明の光検出器では、被検出光が第１及び第
２の受光素子の双方に入射されている。第１の受光素子
が感光する波長よりも長い波長の光が入射したとき、こ
の光は検出されず、第１及び第２の受光素子はハイイン
ピーダンスのままで極僅かしか電流が流れない。第１の
受光素子が感光する波長よりも短く第２の受光素子が感
光する波長よりも長い光が入射したとき、この光は第１
の受光素子で検出されるので、第１の受光素子はローイ
ンピーダンスになる。第２の受光素子はハイインピーダ
ンスのままであるので、第１の受光素子の両端の電圧は
下がる。このとき、第１の受光素子が感光する波長は長
波長にシフトする。第１の受光素子が感光する波長近傍
では、これによって第１の受光素子のインピーダンスの
変化は急峻なものになる。In the photodetector of the present invention, the light to be detected is incident on both the first and second light receiving elements. When light having a wavelength longer than the wavelength that the first light receiving element is exposed to is incident, this light is not detected, and the first and second light receiving elements remain in high impedance, and only a very small amount of current flows. When light having a wavelength shorter than the wavelength that the first light receiving element is exposed and longer than the wavelength that the second light receiving element is exposed to is incident, this light is
The first light receiving element has a low impedance. Since the second light receiving element remains high impedance, the voltage across the first light receiving element drops. At this time, the wavelength with which the first light receiving element is exposed shifts to a long wavelength. In the vicinity of the wavelength at which the first light receiving element is exposed, this causes a steep change in the impedance of the first light receiving element.
【０００７】また、第２の受光素子が感光する波長より
も短い光が入射したとき、第２の受光素子はローインピ
ーダンスになって第１の受光素子の両端の電圧は下が
り、第２の受光素子が感光する波長は長波長にシフトす
る。第２の受光素子が感光する波長近傍でも、同様に第
２の受光素子のインピーダンスの変化は急峻なものにな
る。When light having a wavelength shorter than that of the second light receiving element is incident, the second light receiving element has a low impedance, the voltage across the first light receiving element is lowered, and the second light receiving element is received. The wavelength at which the device is exposed shifts to longer wavelengths. Even in the vicinity of the wavelength at which the second light receiving element is exposed, the impedance of the second light receiving element also changes sharply.
【０００８】このようなポジティブフィードバック効果
により、第１の受光素子が感光する波長よりも短く第２
の受光素子が感光する波長よりも長い光が鋭敏に検出さ
れる。Due to such a positive feedback effect, the wavelength shorter than the wavelength at which the first light receiving element is exposed to light
Light having a wavelength longer than that of the light receiving element is sensitively detected.
【０００９】受光素子が多重量子井戸をもつものである
場合、ポテンシャル構造は、印加される逆バイアスによ
り、井戸構造で干渉しあってサブバンドができている状
態から干渉がなくなった状態になる。これにより逆バイ
アスが大きい時は吸収波長端が短波長側にシフトし、逆
バイアスが小さい時は吸収波長端が長波長側にシフトす
る。When the light receiving element has multiple quantum wells, the potential structure changes from a state in which the well structure interferes with each other to form subbands to a state in which there is no interference due to the reverse bias applied. As a result, when the reverse bias is large, the absorption wavelength end shifts to the short wavelength side, and when the reverse bias is small, the absorption wavelength end shifts to the long wavelength side.
【００１０】[0010]
【実施例】本発明の実施例を図面を参照して説明する。Embodiments of the present invention will be described with reference to the drawings.
【００１１】図１（ａ）は、本発明の光検出器を示した
もので、（ｂ）はその等価回路を示したものである。こ
の光検出器は、モノリシックに形成されており、受光素
子部Ｄ１，Ｄ２に逆バイアスがかかるように直列に接続
し、受光素子部Ｄ２のアノード（受光素子部Ｄ１のカソ
ード）を検出出力ＯＵＴとしている。抵抗Ｒは受光素子
部Ｄ１，Ｄ２がともに通電状態となったときに電流を制
限するための保護抵抗である。FIG. 1A shows a photodetector of the present invention, and FIG. 1B shows an equivalent circuit thereof. This photodetector is monolithically formed, and is connected in series so that a reverse bias is applied to the light receiving element sections D1 and D2, and the anode of the light receiving element section D2 (cathode of the light receiving element section D1) is used as the detection output OUT. There is. The resistor R is a protective resistor for limiting the current when the light receiving element portions D1 and D2 are both energized.
【００１２】受光素子部Ｄ１，Ｄ２は、ｐｉｎフォトダ
イオードで、そのｉ層にＭＱＷ構造（MUTI-QUANTUM WEL
L ，量子井戸構造）を有するものである。このｉ層には
ＭＱＷ構造のバリア層が設けられ、このバリア層は、電
子の波動の広がりに比べて狭く形成されている。電子が
トンネル効果により隣の井戸に遷移するようになってい
る。そのため、電子同士が干渉しあってサブバンドが形
成されている（図２（ａ）参照）。図２（ｂ）は、バリ
ア層が厚く電子が井戸に局在している状態を比較のため
に示したものである。このような受光素子部に逆バイア
スをかけると、ポテンシャル構造が変化し電子がトンネ
ルしなくなってサブバンドが分裂する。これによって、
電子のエネルギー準位が高くなってブルーシフトする
（Wannier Stark 効果）。即ち、受光素子部Ｄ１，Ｄ２
の光吸収特性は、図３に示すような変化を示すものにな
っている（この図で波をうってる部分はエキシントン準
位による）。受光素子部Ｄ１の吸収波長端（バイアス時
λ1 ’，非バイアス時λ1，但し「λ1 ’＜λ1 」）
は、受光素子部Ｄ２の吸収波長端（バイアス時λ2 ’，
非バイアス時λ2 、但し「λ2 ’＜λ2 」）よりも、大
きな波長になるように作り込まれている。The light receiving element portions D1 and D2 are pin photodiodes, and an MQW structure (MUTI-QUANTUM WEL
L, quantum well structure). The i-layer is provided with a barrier layer having an MQW structure, and the barrier layer is formed narrower than the spread of the wave of electrons. The electrons are transitioning to the next well due to the tunnel effect. Therefore, the electrons interfere with each other to form a subband (see FIG. 2A). FIG. 2B shows a state in which the barrier layer is thick and electrons are localized in the well for comparison. When a reverse bias is applied to such a light receiving element portion, the potential structure changes, electrons do not tunnel, and the subbands split. by this,
The electron energy level rises and blue shifts (Wannier Stark effect). That is, the light receiving element sections D1 and D2
Shows the change as shown in FIG. 3 (the waved portion in this figure depends on the Exxington level). Absorption wavelength edge of light receiving element D1 (λ 1 'when biased, λ 1 when not biased, where "λ 1 '<λ 1 ")
Is the absorption wavelength end of the light receiving element D2 (when biased λ 2 ',
Non-bias when λ 2, where "λ 2 '<λ 2") than have been built in so that the large wavelength.
【００１３】つぎに、この光検出器の動作について説明
する。Next, the operation of this photodetector will be described.
【００１４】受光素子部Ｄ１，Ｄ２に光が入射してお
り、入射光の波長が波長λ1 ’よりも大きいとき、受光
素子部Ｄ１，Ｄ２はいずれも感光せず、ハイインピーダ
ンスとなっている。受光素子部Ｄ１，Ｄ２及び抵抗Ｒで
決まる漏れ電流しか流れない。検出出力ＯＵＴにつなが
れた負荷抵抗ＲL により受光素子部Ｄ２の両端の電圧は
低くなっている。そのため、受光素子部Ｄ１には高い逆
バイアス電圧がかかり、受光素子部Ｄ２には低い逆バイ
アス電圧がかかっている。When light is incident on the light receiving element portions D1 and D2 and the wavelength of the incident light is larger than the wavelength λ 1 ', neither of the light receiving element portions D1 and D2 is exposed to light and has a high impedance. .. Only a leak current determined by the light receiving element portions D1 and D2 and the resistor R flows. The voltage across the light receiving element D2 is lowered by the load resistance R L connected to the detection output OUT. Therefore, a high reverse bias voltage is applied to the light receiving element section D1, and a low reverse bias voltage is applied to the light receiving element section D2.
【００１５】入射光の波長が波長λ1 ’よりも小さくな
ると（但し、波長λ2 ’よりも大きい）、受光素子部Ｄ
１に光電流が流れ、ローインピーダンスになる。受光素
子部Ｄ２はハイインピーダンスのままであるので、受光
素子部Ｄ２の両端の電圧は高くなる。一方、受光素子部
Ｄ１の両端の電圧は低くなり、その吸収波長端は波長λ
1 にシフトする（長波長になる）。これによって受光素
子部Ｄ１の光電流が増加し、よりローインピーダンスに
なって、受光素子部Ｄ２の両端の電圧は急峻に立ち上が
る。When the wavelength of the incident light becomes smaller than the wavelength λ 1 ′ (however, it is larger than the wavelength λ 2 ′), the light receiving element portion D
A photocurrent flows in 1 and becomes low impedance. Since the light receiving element section D2 remains high impedance, the voltage across the light receiving element section D2 becomes high. On the other hand, the voltage at both ends of the light receiving element section D1 becomes low, and the absorption wavelength end becomes the wavelength λ.
Shift to 1 (longer wavelength). As a result, the photocurrent of the light receiving element section D1 is increased to have a lower impedance, and the voltage across the light receiving element section D2 rises sharply.
【００１６】そして、入射光の波長が波長λ2 ’よりも
小さくなると、受光素子部Ｄ２にも光電流が流れ、受光
素子部Ｄ１，Ｄ２の両方がローインピーダンスになる。
光電流及び抵抗Ｒによる電圧降下で光素子部Ｄ２の両端
の電圧は低くなる。これによってその吸収波長端は波長
λ1 にシフトし（長波長になる）、受光素子部Ｄ１の光
電流がより増加し、よりローインピーダンスになって、
受光素子部Ｄ２の両端の電圧は急峻に立ち下がる。When the wavelength of the incident light becomes smaller than the wavelength λ 2 ′, photocurrent also flows in the light receiving element section D2, and both the light receiving element sections D1 and D2 become low impedance.
The voltage drop due to the photocurrent and the resistance R lowers the voltage across the optical element section D2. As a result, the absorption wavelength end shifts to the wavelength λ 1 (becomes a long wavelength), the photocurrent of the light receiving element D1 further increases, and the impedance becomes lower,
The voltage across the light receiving element section D2 falls sharply.
【００１７】このようなポジティブフィードバック動作
がなされ、波長を変化させたとき、図４に示されるよう
な出力波形の変化が得られる。この動作は量子効果によ
るため、特に、波長λ1 ’，λ2 ’近傍の立上がり立ち
下がりは非常に急峻で、外部にアンプを付加することな
しにこのような動作が得られる。また、回路構成が簡単
であり、フィルタなどの光学部品が不要であるため、集
積化が可能になっており非常に小型になる。When such a positive feedback operation is performed and the wavelength is changed, a change in output waveform as shown in FIG. 4 is obtained. Since this operation is due to the quantum effect, the rising and falling in the vicinity of the wavelengths λ 1 'and λ 2 ' are very steep, and such an operation can be obtained without adding an external amplifier. Further, since the circuit configuration is simple and no optical parts such as a filter are required, integration is possible and the size is very small.
【００１８】本発明は前述の実施例に限らず様々な変形
が可能である。The present invention is not limited to the above-mentioned embodiment, but various modifications can be made.
【００１９】例えば、抵抗Ｒは電流制限用であるから、
これにかえてトランジスタ，ＦＥＴで構成された定電流
源としても良い。また、正電圧のバイアスをかけている
が、極性をかえて負電圧のバイアスをかけるようにして
も良い。For example, since the resistor R is for current limiting,
Alternatively, a constant current source composed of transistors and FETs may be used. Further, although a positive voltage bias is applied, a negative voltage bias may be applied by changing the polarity.
【００２０】[0020]
【発明の効果】以上の通り本発明の光検出器によれば、
第１及び第２の受光素子部の吸収波長端は、それぞれ光
を検出すると長波長側にシフトし、それらの受光素子の
インピーダンスの変化は急峻なものになる。そのため、
増幅器などの回路を付加することなしに、第１及び第２
の受光素子で与えられる特定の波長帯域の光を鋭敏に検
出することができる。As described above, according to the photodetector of the present invention,
When the light is detected, the absorption wavelength ends of the first and second light receiving element portions are shifted to the long wavelength side, and the impedance of these light receiving elements changes steeply. for that reason,
The first and second without adding a circuit such as an amplifier
It is possible to sensitively detect light in a specific wavelength band provided by the light receiving element.
【図１】実施例の構成図。FIG. 1 is a configuration diagram of an embodiment.
【図２】ｉ層のバンド図。FIG. 2 is a band diagram of the i layer.
【図３】光吸収特性図。FIG. 3 is a light absorption characteristic diagram.
【図４】出力波形図。FIG. 4 is an output waveform diagram.
【図５】従来例の構成図。FIG. 5 is a configuration diagram of a conventional example.
Ｄ１，Ｄ２…受光素子部。 D1, D2 ... Light receiving element section.
Claims (2)
波長端が長波長側にシフトする第１の受光素子と、 前記第１の受光素子よりも短い吸収波長端を有するとと
もに逆バイアスの大きさに応じてその吸収波長端が長波
長側にシフトする第２の受光素子とを有し、 前記第１及び第２の受光素子に逆バイアスが印加される
ように直列接続するとともに被検出光が前記第１及び第
２の受光素子の双方に入射されるようにしたことを特徴
とする光検出器。1. A first light-receiving element whose absorption wavelength end shifts to a longer wavelength side when the reverse bias voltage decreases, and an absorption wavelength end shorter than the first light-receiving element and having a reverse bias magnitude. And a second light receiving element whose absorption wavelength end is shifted to the long wavelength side in accordance with the second light receiving element. The first and second light receiving elements are connected in series so that a reverse bias is applied, and the detected light is A photodetector characterized in that it is made incident on both the first and second light receiving elements.
層と、第２導電層と、前記第１導電層及び前記第２導電
層の間に設けられ、半導体超格子をなす多重量子井戸層
とで構成されていることを特徴とする請求項１記載の光
検出器。2. The first and second light receiving elements are provided between a first conductive layer, a second conductive layer, and the first conductive layer and the second conductive layer, and form a semiconductor superlattice. The photodetector according to claim 1, wherein the photodetector comprises a quantum well layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6044392A JPH05264339A (en) | 1992-03-17 | 1992-03-17 | Photodetector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6044392A JPH05264339A (en) | 1992-03-17 | 1992-03-17 | Photodetector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05264339A true JPH05264339A (en) | 1993-10-12 |
Family
ID=13142427
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6044392A Pending JPH05264339A (en) | 1992-03-17 | 1992-03-17 | Photodetector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05264339A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022003813A1 (en) * | 2020-06-30 | 2022-01-06 | シャープ株式会社 | Electromagnetic wave sensor device and display device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03227578A (en) * | 1989-03-03 | 1991-10-08 | Mitsubishi Electric Corp | Optical element apparatus |
-
1992
- 1992-03-17 JP JP6044392A patent/JPH05264339A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03227578A (en) * | 1989-03-03 | 1991-10-08 | Mitsubishi Electric Corp | Optical element apparatus |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022003813A1 (en) * | 2020-06-30 | 2022-01-06 | シャープ株式会社 | Electromagnetic wave sensor device and display device |
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