JPH0834316B2 - Semiconductor radiation detector - Google Patents
Semiconductor radiation detectorInfo
- Publication number
- JPH0834316B2 JPH0834316B2 JP62110215A JP11021587A JPH0834316B2 JP H0834316 B2 JPH0834316 B2 JP H0834316B2 JP 62110215 A JP62110215 A JP 62110215A JP 11021587 A JP11021587 A JP 11021587A JP H0834316 B2 JPH0834316 B2 JP H0834316B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- radiation detector
- semiconductor radiation
- detector
- teo
- 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.)
- Expired - Fee Related
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Landscapes
- Electrodes Of Semiconductors (AREA)
- Light Receiving Elements (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は放射線線量計，医療用放射線診断装置，工業
用Ｘ線非破壊検査装置などに用いる半導体放射線検出器
に関するものである。Description: TECHNICAL FIELD The present invention relates to a semiconductor radiation detector used in a radiation dosimeter, a medical radiation diagnostic apparatus, an industrial X-ray nondestructive inspection apparatus, and the like.
従来の技術 一般に半導体放射線検出器にはケイ素（Si），ゲルマ
ニウム（Ge）などの元素半導体より構成されるものと、
テルル化カドミウム（CdTe），砒化ガリウム（GaAs），
ヨウ化水銀（HgI2）などの化合物半導体により構成され
るものがある。これらの半導体のうち、CdTeは禁制帯幅
が室温で約1.5eVと広く室温動作が可能であるとともに
放射線の吸収係数が大きいので高感度が得られる。CdTe
放射線検出器には、低キャリア濃度の高抵抗CdTe結晶の
対向面にオーミック接合電極を形成し、結晶全体を空乏
層すなわち放射線の有感領域とした全空乏層型検出器を
はじめ、一方の面に表面障壁電極、他方にオーミック接
合電極を形成し、障壁近傍に発生する空乏層において放
射線を検出する表面障壁型検出器、あるいは一方の面に
Pn接合、他方の面にオーミック接合を形成し逆バイアス
電圧を印加することによりPn接合に発生する空乏層で放
射線を検出するPn接合型検出器がある。これらのCdTe放
射線検出器のうち全空乏層型検出器は検出器全体が有感
層となるため非常に高感度である。2. Description of the Related Art In general, semiconductor radiation detectors are composed of elemental semiconductors such as silicon (Si) and germanium (Ge).
Cadmium telluride (CdTe), gallium arsenide (GaAs),
Some are composed of compound semiconductors such as mercury iodide (HgI 2 ). Among these semiconductors, CdTe has a wide bandgap of about 1.5 eV at room temperature and can operate at room temperature, and has a high radiation absorption coefficient, so that high sensitivity can be obtained. CdTe
For the radiation detector, an ohmic junction electrode is formed on the opposing surface of a high-resistance CdTe crystal with a low carrier concentration, and a depletion layer type detector in which the entire crystal is used as a depletion layer, that is, a radiation-sensitive region, is included. Surface barrier electrode on the other side, ohmic junction electrode on the other side, and a surface barrier type detector that detects radiation in the depletion layer generated near the barrier, or on one side
There is a Pn junction detector, in which an ohmic junction is formed on the other surface and a reverse bias voltage is applied to detect radiation in a depletion layer generated in the Pn junction. Of these CdTe radiation detectors, the fully depleted layer type detector is very sensitive because the whole detector is a sensitive layer.
以上に述べた半導体放射線検出器のオーミック接合電
極は金（Au），白金（Pt），ニッケル（Ni），カルシウ
ム（Cu），アルミニウム（Al），インジウム（In）の蒸
着、Ptの無電解メッキなど、CdTe結晶上に直接被着する
方法が用いられていた。The ohmic contact electrodes of the semiconductor radiation detector described above are vapor deposition of gold (Au), platinum (Pt), nickel (Ni), calcium (Cu), aluminum (Al), indium (In), electroless plating of Pt. For example, a method of directly depositing on a CdTe crystal has been used.
発明が解決しようとする問題点 全空乏層型検出器を構成するためには、結晶のキャリ
ア濃度が1012cm-3以下であることが必要であり、また、
表面障壁型検出器、Pn接合型検出器の空乏層幅は結晶の
キャリア濃度が小さいほど広く、そして高感度が得られ
るものである。従ってCdTe結晶は非常に高抵抗のものが
用いられる。Problems to be Solved by the Invention In order to construct a fully depleted layer type detector, the carrier concentration of the crystal needs to be 10 12 cm −3 or less, and
The width of the depletion layer of the surface barrier type detector and the Pn junction type detector is wider as the carrier concentration of the crystal is smaller, and high sensitivity can be obtained. Therefore, a CdTe crystal having a very high resistance is used.
しかしながら、高抵抗CdTe結晶に良好なオーミック接
合を形成することは一般に困難である。つまり前記の蒸
着あるいは無電解メッキの方法で電極構成したCdTe放射
線検出器は、いずれも金属電極とCdTe結晶層との接触面
にバリア層が形成されるものであり、電極界面にバリア
層が存在するために外部印加電界がバリア層に集中し、
有感層を形成するための電界が減少し、有感層の厚みが
小さくなり感度が低下するものである。また、有感層で
発生した電荷が電極界面のバリア層にトラップされ、電
極とCdTe結晶との界面に空間電荷が蓄積され易くなり、
電荷収集効率の低下すなわち検出器特性が悪化するとい
う問題があった。また、蓄積される空間電荷量は電圧印
加したのち時間経過とともに増加し、この蓄積された電
荷により検出器を長時間動作させると感度が時間経過と
ともに低下するなどの問題があった。However, it is generally difficult to form a good ohmic junction in a high resistance CdTe crystal. That is, in any of the CdTe radiation detectors whose electrodes are formed by the above vapor deposition or electroless plating method, a barrier layer is formed on the contact surface between the metal electrode and the CdTe crystal layer, and the barrier layer exists at the electrode interface. In order to do this, the externally applied electric field concentrates on the barrier layer,
The electric field for forming the sensitive layer decreases, the thickness of the sensitive layer decreases, and the sensitivity decreases. Further, the charges generated in the sensitive layer are trapped in the barrier layer at the electrode interface, and space charges are easily accumulated at the interface between the electrode and the CdTe crystal,
There is a problem that the charge collection efficiency is lowered, that is, the detector characteristics are deteriorated. Further, the amount of space charge accumulated increases with time after applying a voltage, and if the detector is operated for a long time by the accumulated charge, there is a problem that the sensitivity decreases with time.
本発明は上記問題点を解決するもので、良好なオーミ
ック接合を備え、長時間動作させても検出感度が良好か
つ安定な半導体放射線検出器を提供することを目的とす
るものである。The present invention solves the above problems, and an object of the present invention is to provide a semiconductor radiation detector which has a good ohmic junction and has good detection sensitivity and stability even when operated for a long time.
問題点を解決するための手段 上記目的を達成するために本発明の半導体放射線検出
器は、テルル化カドミウム結晶と金属電極層の間にテル
ル酸化物層を有するものである。Means for Solving the Problems To achieve the above object, the semiconductor radiation detector of the present invention has a tellurium oxide layer between a cadmium telluride crystal and a metal electrode layer.
作用 上記構成において、テルル酸化物（TeOx）層はテルル
化カドミウム（CdTe）結晶に比べて抵抗率が低く、かつ
キャリア濃度が大きい。したがって、例えばＰ形CdTe結
晶と金属電極層の間にTeOx層を設けた場合、TeOx層はP+
層と同様な作用を有し、金属電極層との接合面に障壁の
ない良好なオーミック接合を形成することができる。従
って、半導体放射線検出器を長時間動作させても検出感
度が変化せず極めて良好かつ安定な放射線検出が可能と
なる。Action In the above structure, the tellurium oxide (TeO x ) layer has a lower resistivity and a higher carrier concentration than the cadmium telluride (CdTe) crystal. Thus, for example, the case of providing a TeO x layer between the P-type CdTe crystal and a metal electrode layer, TeO x layer P +
It has the same action as that of the layer and can form a good ohmic contact without a barrier on the joint surface with the metal electrode layer. Therefore, even if the semiconductor radiation detector is operated for a long time, the detection sensitivity does not change, and extremely good and stable radiation detection can be performed.
実施例 以下に本発明の一実施例の半導体放射線検出器につい
て図面を参照しながら説明する。Embodiment A semiconductor radiation detector according to an embodiment of the present invention will be described below with reference to the drawings.
第１図は本発明の一実施例の半導体放射線検出器の断
面図である。第１図において、108〜1010Ωcmの高抵抗C
dTe結晶１の一方の面に、Te層を真空蒸着した後、熱酸
化を行ないTeOx層２を形成し、次に、TeOx層２上に真空
蒸着方によりAu電極３を形成している。またCdTe結晶１
の他方の面にも同様な方法でTeOx層２とAu電極３を積層
し全空乏層型CdTe放射線検出器が構成されている。FIG. 1 is a sectional view of a semiconductor radiation detector according to an embodiment of the present invention. In Fig. 1, high resistance C of 10 8 to 10 10 Ωcm
on one surface of dTe crystal 1, it was vacuum deposited Te layer, to form a TeO x layer 2 subjected to thermal oxidation, then to form the Au electrode 3 by vacuum vapor deposition side on TeO x layer 2 . Also CdTe crystal 1
A TeO x layer 2 and an Au electrode 3 are laminated on the other surface of the same in the same manner as the full depletion layer type CdTe radiation detector.
本実施例の半導体放射線検出器の電流−電圧特性を第
２図に示す。第２図から明らかなように、実施例に示さ
れた半導体放射線検出器は良好なオーミック特性を示
す。第３図は検出器感度の時間変化を測定した結果を示
す特性図である。第３図の横軸は検出器を動作し始めて
からの経過時間、縦軸は初期感度を１とした相対感度で
ある。本検出器で感度の時間変化がない。つまり、Au電
極３とTeOx層２の接合界面にバリア層がなく、空間電荷
が蓄積されていないことを示す。The current-voltage characteristics of the semiconductor radiation detector of this example are shown in FIG. As is apparent from FIG. 2, the semiconductor radiation detector shown in the example shows a good ohmic characteristic. FIG. 3 is a characteristic diagram showing the results of measuring the change in detector sensitivity with time. The horizontal axis of FIG. 3 is the elapsed time after the detector starts operating, and the vertical axis is the relative sensitivity where the initial sensitivity is 1. This detector has no sensitivity change over time. That is, there is no barrier layer at the junction interface between the Au electrode 3 and the TeO x layer 2 and no space charge is accumulated.
なおTeOx層２の形成方法としては、化学気相成長（CV
D）法、分子線エピタキシー（MBE）法、液相エピタキシ
ー（LPE）法、プラズマCVD法により形成したTeを酸化す
る方法がある。また、TeとTeOxの真空蒸着やCVD法、MBE
法、MOCVD法、LPE法、プラズマCVD法等によるTeOxの披
着による方法もある。The TeO x layer 2 can be formed by chemical vapor deposition (CV
D) method, molecular beam epitaxy (MBE) method, liquid phase epitaxy (LPE) method, and a method of oxidizing Te formed by plasma CVD method. In addition, vacuum deposition of Te and TeO x , CVD method, MBE
Law, MOCVD method, LPE method, a method according披着of TeO x by plasma CVD method or the like is.
さらにTeOx層はCdTe結晶のドライエッチングまたはウ
エットエッチングにより、あるいは無電解メッキにより
金属電極を構成する際にメッキ液の成分を調整すること
により同時にCdを選択的にエッチングし、CdTe結晶表面
にTe過剰層を形成し、これを熱酸化することによっても
得られる。Further, the TeO x layer is selectively etched at the same time by dry etching or wet etching of the CdTe crystal, or by adjusting the components of the plating solution when forming the metal electrode by electroless plating, so that the CdTe crystal surface is coated with Te. It can also be obtained by forming an excess layer and thermally oxidizing it.
なお以上のような方法で形成したTeOx層は通常TeとTe
Oxの混在した層となるが、テルルがすべて酸化したTeO2
のみでも同様な効果が得られる。Note that the TeO x layer formed by the above method is usually Te and Te.
TeO 2 is a layer in which O x is mixed, but tellurium is completely oxidized.
The same effect can be obtained by using only.
金属電極層としてはPt,Al,Ni,Cu等があり、これらの
形成方法としては、無電解メッキ，電解メッキ，スパッ
タ法などがある。これらいずれの方法によって電極形成
を行なっても同様の特性が得られる。The metal electrode layer includes Pt, Al, Ni, Cu and the like, and the forming method thereof includes electroless plating, electrolytic plating, sputtering method and the like. The same characteristics can be obtained by forming electrodes by any of these methods.
次に本発明の他の実施例の半導体放射線検出器につい
て第４図を参照しながら説明する。Next, a semiconductor radiation detector according to another embodiment of the present invention will be described with reference to FIG.
第４図は本発明の他の実施例における半導体放射線検
出器の断面図である。第４図に示す半導体放射線検出器
は、CdTe結晶のいずれか一方の面に金属電極層３をTeOx
層２の介在なしに直接被着させ表面障壁電極とし、他方
の面に前述の第１の実施例と同様にTeOx層２を介在させ
金属電極層３を積層しオーミック接合とした表面障壁型
放射線検出器である。FIG. 4 is a sectional view of a semiconductor radiation detector according to another embodiment of the present invention. In the semiconductor radiation detector shown in FIG. 4, the metal electrode layer 3 is formed on one surface of the CdTe crystal by TeO x.
A surface barrier electrode is formed by directly depositing without interposing the layer 2 to form a surface barrier electrode, and forming a metal electrode layer 3 on the other surface with a TeO x layer 2 interposed therebetween in the same manner as in the first embodiment to form an ohmic contact. It is a radiation detector.
本実施例の検出器は、一方の面にTeOx層２を介在させ
て構成した良好なオーミック接合を有するため、実験の
結果、表面障壁電極界面に電解が集中し、有感層が大き
くなり高い感度が得られた。Since the detector of the present example has a good ohmic junction formed by interposing the TeO x layer 2 on one surface, as a result of the experiment, electrolysis is concentrated on the surface barrier electrode interface and the sensitive layer becomes large. High sensitivity was obtained.
発明の効果 本発明によれば、テルル化カドミウムと金属電極層の
間にテルル酸化物層を設けた構成としたために、金属電
極層とテルル化カドミウム結晶の間にバリア層が形成さ
れず、良好なオーミック接合が得られ、放射線の検出効
率が高く、かつ感度の時間変化がない信頼性の高い半導
体放射線検出器を提供できるものである。According to the present invention, since the tellurium oxide layer is provided between the cadmium telluride and the metal electrode layer, the barrier layer is not formed between the metal electrode layer and the cadmium telluride crystal, which is excellent. It is possible to provide a highly reliable semiconductor radiation detector in which a high ohmic junction is obtained, the radiation detection efficiency is high, and the sensitivity does not change with time.
第１図は本発明の一実施例の半導体放射線検出器の断面
図、第２図は同半導体放射線検出器の電流−電圧特性
図、第３図は同半導体放射線検出器における検出感度の
時間変化についての実験結果を示す特性図、第４図は本
発明の他の実施例の半導体放射線検出器の断面図であ
る。 １……テルル化カドミウム（CdTe）結晶、２……テルル
酸化物（TeOx）層、３……金属電極層。FIG. 1 is a sectional view of a semiconductor radiation detector according to an embodiment of the present invention, FIG. 2 is a current-voltage characteristic diagram of the semiconductor radiation detector, and FIG. 3 is a time change of detection sensitivity in the semiconductor radiation detector. FIG. 4 is a characteristic diagram showing the experimental result of FIG. 4, and FIG. 4 is a sectional view of a semiconductor radiation detector of another embodiment of the present invention. 1 ... Cadmium telluride (CdTe) crystal, 2 ... Tellurium oxide (TeO x ) layer, 3 ... Metal electrode layer.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０１Ｌ 31/108 Ｈ０１Ｌ 31/10 Ｃ (72)発明者 馬場 末喜 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 (72)発明者 渡辺 正則 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 (56)参考文献 特開 昭57−64981（ＪＰ，Ａ) 特開 昭57−64983（ＪＰ，Ａ) 特開 昭57−64986（ＪＰ，Ａ) 特開 昭59−175121（ＪＰ，Ａ)─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification number Internal reference number FI Technical indication location H01L 31/108 H01L 31/10 C (72) Inventor Sueki Baba 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Masanori Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 57-64981 (JP, A) JP 57-64983 ( JP, A) JP 57-64986 (JP, A) JP 59-175121 (JP, A)
Claims (2)
の面に形成されたテルル酸化物層と、このテルル酸化物
層およびテルル化カドミウム結晶上に形成された金属電
極層を備えた半導体放射線検出器。1. A semiconductor radiation detector comprising a tellurium oxide layer formed on at least one surface of a cadmium telluride crystal, and a metal electrode layer formed on the tellurium oxide layer and the cadmium telluride crystal.
の混在する層であることを特徴とする特許請求の範囲第
１項記載の半導体放射線検出器。2. The semiconductor radiation detector according to claim 1, wherein the tellurium oxide layer is a layer in which tellurium and tellurium dioxide are mixed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62110215A JPH0834316B2 (en) | 1987-05-06 | 1987-05-06 | Semiconductor radiation detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62110215A JPH0834316B2 (en) | 1987-05-06 | 1987-05-06 | Semiconductor radiation detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63274182A JPS63274182A (en) | 1988-11-11 |
| JPH0834316B2 true JPH0834316B2 (en) | 1996-03-29 |
Family
ID=14529985
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62110215A Expired - Fee Related JPH0834316B2 (en) | 1987-05-06 | 1987-05-06 | Semiconductor radiation detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0834316B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6242954B1 (en) * | 2016-07-11 | 2017-12-06 | 浜松ホトニクス株式会社 | Radiation detector |
-
1987
- 1987-05-06 JP JP62110215A patent/JPH0834316B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63274182A (en) | 1988-11-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6255708B1 (en) | Semiconductor P-I-N detector | |
| JP3338139B2 (en) | Diamond Schottky diode and gas sensor and chemical substance sensor using the same | |
| US3805601A (en) | High sensitivity semiconductor strain gauge | |
| Goodman et al. | Photoemission of electrons from metals into silicon dioxide | |
| EP0777277A1 (en) | Ionizing radiation detector | |
| Williams | Injection by internal photoemission | |
| JP4037917B2 (en) | X-ray detection element and method of operating the element | |
| JPH0834316B2 (en) | Semiconductor radiation detector | |
| US6975012B2 (en) | Semiconductor radiation detector having voltage application means comprises InxCdyTez on CdTe semiconductor substrate | |
| US4524378A (en) | Anodizable metallic contacts to mercury cadmium telleride | |
| US20050056829A1 (en) | Reducing dark current of photoconductor using heterojunction that maintains high x-ray sensitivity | |
| JPH01138486A (en) | Multichannel type semiconductor radiation detector | |
| USRE29009E (en) | High sensitivity semiconductor strain gauge | |
| JPH08236799A (en) | Semiconductor radiation detecting element and rectifying element | |
| JPS6070774A (en) | Detector for radiation | |
| JPS63268278A (en) | Semiconductor radiation detector | |
| JPH085749A (en) | Semiconductor radiation detector and manufacturing method thereof | |
| JPS63316485A (en) | Semiconductor radiation detector | |
| JP2001221763A (en) | Nitrogen oxide gas sensor | |
| JPH06112515A (en) | Semiconductor radiation detector and manufacturing method thereof | |
| JPH07325157A (en) | Semiconductor radiation detector | |
| JPH0831619B2 (en) | Infrared detector | |
| JPH0648732B2 (en) | Photovoltaic infrared detector | |
| Takami et al. | Evaluation of various electrode metals for ultra-high purity P-type Si surface barrier detectors | |
| JPS63114178A (en) | Manufacture of infrared detecting element |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |