JPH0497990A - Production of cdte single crystal - Google Patents
Production of cdte single crystalInfo
- Publication number
- JPH0497990A JPH0497990A JP2210276A JP21027690A JPH0497990A JP H0497990 A JPH0497990 A JP H0497990A JP 2210276 A JP2210276 A JP 2210276A JP 21027690 A JP21027690 A JP 21027690A JP H0497990 A JPH0497990 A JP H0497990A
- Authority
- JP
- Japan
- Prior art keywords
- single crystal
- resistivity
- crystal
- cdte single
- heat treatment
- 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.)
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- Light Receiving Elements (AREA)
- Measurement Of Radiation (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
【発明の詳細な説明】
且班Ω五丘斑互
本発明は、放射線検出素子用等として有用な高抵抗Ｃｄ
Ｔｅ単結晶の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention provides high-resistance Cd useful for radiation detection elements, etc.
The present invention relates to a method for producing a Te single crystal.
皿米五羽
ＣｄＴｅ単結晶は放射線検出素子等に有用であり、その
特性向上、特に高エネルギー分解能化をめざして従来か
らＣｄＴｅ単結晶の製造方法が検討されている。BACKGROUND OF THE INVENTION CdTe single crystals are useful for radiation detection elements and the like, and methods for producing CdTe single crystals have been studied with the aim of improving their characteristics, particularly achieving higher energy resolution.
高エネルギー分解能を達成するための結晶特性としでは
、主に次の２点が重要である。Regarding crystal properties for achieving high energy resolution, the following two points are mainly important.
第１点は、抵抗率が高いことである。抵抗率が低いと放
射線検出器の信号ノイズが増大し好ましくなく、］Ｘ１
．０”０ｃｍ以上の値が必要である。The first point is that the resistivity is high. If the resistivity is low, the signal noise of the radiation detector will increase, which is undesirable.
．． A value of 0"0cm or more is required.
第２点はキャリアライフタイムが大きいことである。キ
ャリアライフタイムが小さいと、キャリア収集効率が低
下し、エネルギー分解能が低下する。The second point is that the career lifetime is long. A small carrier lifetime reduces carrier collection efficiency and reduces energy resolution.
以上のことから、放射線検品素子用の結晶の製造条件の
検討は、高抵抗率化、キャリアライフタイムの増大の２
点に注目して行なわれてきた。Based on the above, it is important to consider the manufacturing conditions of crystals for radiation inspection elements in order to achieve two goals: high resistivity and increased carrier lifetime.
This has been done with a focus on the points.
第１魚目の高抵抗率化に対しては、結晶成長時に塩素を
ドープして抵抗率を向上する事が報告されている。In order to increase the resistivity of the first fish, it has been reported that chlorine is doped during crystal growth to improve the resistivity.
第２黒目のキャリアライフタイムの増大に関しては、結
晶の純度の向上によって達成される事が報告されている
。It has been reported that the carrier lifetime of the second iris can be increased by improving the purity of the crystal.
が る赴１し医
従来から、高抵抗率の結晶を得るためには、結晶中に添
加する塩素濃度を増加することが効果あることが知られ
ている。しかし、塩素濃度が高くなるほどキャリアライ
フタイムは低下する傾向があるために、放射線検出素子
に適した充分抵抗率が高く、しかもキャリアライフタイ
ムも大きい結晶を得ることが出来ないという問題点があ
った。It has long been known that increasing the concentration of chlorine added to the crystal is effective in obtaining crystals with high resistivity. However, as the carrier lifetime tends to decrease as the chlorine concentration increases, there was a problem in that it was not possible to obtain crystals with sufficiently high resistivity and long carrier lifetime suitable for radiation detection elements. .
すなわち、放射線検出素子として使用可能な抵抗率を得
るためには、塩素の添加量をある程度大きな量にせざる
を得す、そのため、キャリアライフタイムが小さくなり
、結果的に、この結晶を使用して作製した放射線検出素
子のエネルギー分解能は満足できる値が得られていない
という間駆があった。In other words, in order to obtain a resistivity that can be used as a radiation detection element, the amount of chlorine added must be increased to a certain extent, which reduces the carrier lifetime, and as a result, this crystal cannot be used. There was a problem that the energy resolution of the fabricated radiation detection element was not satisfactory.
且亙辺璽辰
本発明は、上記の問題点を解決したものであって、放射
線検出素子用のＣｄＴｅ単結晶の製造方法において、塩
素を０．８重量ｐｐｍ以上５重量ｐｐｍ以下の濃度で添
加したＣｄＴｅ単結晶を、真空中、あるいは不活性ガス
中で３５０℃以上４５０℃以下の温度で熱処理すること
を特徴とするＣｄＴｅ単結晶の製造方法に関するもので
ある。The present invention solves the above-mentioned problems, and includes adding chlorine at a concentration of 0.8 ppm to 5 ppm by weight in a method for producing a CdTe single crystal for a radiation detection element. The present invention relates to a method for producing a CdTe single crystal, which is characterized by heat-treating the CdTe single crystal at a temperature of 350° C. or more and 450° C. or less in vacuum or in an inert gas.
を る および
上記の問題点を解決するためには、低塩素濃度でも抵抗
率の高い結晶を得る方法が必要であり、本発明者等は、
結晶を熱処理することで抵抗率が増加することを新たに
見い出し、本発明に至ったものである。In order to solve the above problems, a method is needed to obtain crystals with high resistivity even at low chlorine concentrations, and the present inventors have
The present invention was based on the new discovery that heat treatment of crystals increases resistivity.
本発明における熱処理は真空中あるいはＡｒ、窒素など
の不活性ガス雰囲気下で行う。これは、酸化防止のため
に行なわれる。The heat treatment in the present invention is performed in vacuum or in an inert gas atmosphere such as Ar or nitrogen. This is done to prevent oxidation.
本発明における熱処理温度は３５０℃以上４５０℃以下
である必要がある。熱処理温度が３５０℃未満であって
も、４５０℃を越えても、抵抗率はｌＸｌ０”Ωｃｍ以
下となるため好ましくないからである。特に結晶中の塩
素濃度が小さい場合、この熱処理温度範囲はより一層狭
く限定される。The heat treatment temperature in the present invention needs to be 350°C or more and 450°C or less. This is because, even if the heat treatment temperature is less than 350°C or exceeds 450°C, the resistivity will be less than 1X10"Ωcm, which is undesirable. Especially when the chlorine concentration in the crystal is low, this heat treatment temperature range is more narrowly limited.
例えば、第１図に示すように塩素濃度が１重量ｐｐｍの
結晶の場合、３７０℃以上４００℃以下で熱処理する必
要がある。しかし、塩素濃度が５重量ｐｐｍの結晶の場
合、熱処理温度範囲は３５０℃以上４５０℃以下で熱処
理することで抵抗率はｌＸｌ０°Ωｃｍ以上となる。For example, as shown in FIG. 1, in the case of crystals having a chlorine concentration of 1 ppm by weight, it is necessary to heat-treat the crystal at a temperature of 370° C. or higher and 400° C. or lower. However, in the case of a crystal with a chlorine concentration of 5 ppm by weight, the heat treatment temperature range is 350° C. or higher and 450° C. or lower, so that the resistivity becomes 1×10° Ωcm or higher.
本発明の熱処理は、例えば第２図に示すごとく、塩素が
０．８重量ｐｐｍ以上、５重量ｐｐｍ以下の濃度で添加
された結晶に対して行われる。０゜８重量ｐ’ｐｍ以下
では本発明の熱処理を行っても、結晶の抵抗率は ｌ
Ｘ １０”Ωｃｍ以上に向上しないため、放射線検出素
子用の結晶として使用することが出来ない。５重量ｐｐ
ｍを越える場合は、例えば第３図に示すごとく、本発明
の熱処理を行っても、キャリアライフタイムが低くなる
ため、高性能の放射線検出素子が得られないため効果が
少ない。The heat treatment of the present invention is performed on crystals to which chlorine is added at a concentration of 0.8 ppm or more and 5 ppm or less by weight, for example, as shown in FIG. Even if the heat treatment of the present invention is performed below 0°8 weight p'pm, the resistivity of the crystal is l
X cannot be used as a crystal for radiation detection elements because it does not improve to more than 10" Ωcm. 5 pp by weight
If it exceeds m, as shown in FIG. 3, for example, even if the heat treatment of the present invention is performed, the carrier lifetime will be low, and a high-performance radiation detection element cannot be obtained, so that the effect will be small.
本発明の熱処理時間は、１時間以上、より好ましくは１
５時間以上である。尚、該熱処理はインゴットの状態で
も、ウェハーの状態で行なっても良い。The heat treatment time of the present invention is 1 hour or more, more preferably 1 hour or more.
It is more than 5 hours. Note that the heat treatment may be performed on the ingot or wafer.
［実施例］
塩素濃度１重量ｐｐｍのＣｄＴｅ結晶ウェハを、真空中
で３８５℃で１５時間熱処理した後、約５０′Ｃ／ｈｒ
で室温まで炉冷した結晶を用いて、放射線検出素子を作
製した。[Example] A CdTe crystal wafer with a chlorine concentration of 1 ppm by weight was heat-treated at 385°C for 15 hours in a vacuum, and then heated at approximately 50'C/hr.
A radiation detection element was fabricated using the crystal that was furnace-cooled to room temperature.
この結晶の抵抗率は、２Ｘ１０”Ωｃｍ、キャリアライ
フタイムは電子が１μｓ、ホールが０゜５μｓであった
。このように本発明の処理品は、高抵抗、高キヤリアラ
イフタイムを同時に満足するものであった。The resistivity of this crystal was 2 x 10" Ωcm, and the carrier lifetime was 1 μs for electrons and 0.5 μs for holes. In this way, the processed product of the present invention satisfies both high resistance and high carrier lifetime. Met.
さらに放射線検出素子としての特性は、”４“Ａｍの放
射線（５９，５ｋｅＶのエネルギーをもっている）を測
定したときのピーク強度半値幅が、印加電圧１５Ｖにお
いて５ｋｅＶの良好な分解能が得られた。Further, regarding the characteristics as a radiation detection element, when measuring "4" Am radiation (having energy of 59.5 keV), a good resolution of 5 keV in peak intensity half width at an applied voltage of 15 V was obtained.
［比較例１］
塩素濃度１重量ｐｐｍの結晶を、熱処理をせずに放射線
検出素子を作製した。この結晶の抵抗率は、Ｉ Ｘ １
０’Ωｃｍと低く、そのためキャリアライフタイムも測
定８来なかった。放射線検出素子としての特性は、抵抗
率が低すぎたために、リク電流が大きく、”°”Ａｍの
放射線を測定したところ、なんらスペクトルが得られな
かった。[Comparative Example 1] A radiation detection element was produced using a crystal with a chlorine concentration of 1 ppm by weight without heat treatment. The resistivity of this crystal is I x 1
The carrier lifetime was as low as 0'Ωcm, so the measured carrier lifetime did not reach 8. As for the characteristics as a radiation detection element, since the resistivity was too low, the leakage current was large, and when radiation of "°" Am was measured, no spectrum was obtained.
災１例廟末
本発明により、結晶中塩素濃度が０．８重量ｐｐｍ以上
５重量ｐｐｍという低塩素濃度でも、放射線検出素子を
作製するのに充分な抵抗率の高い結晶を得ることが出来
るようになった。このため、この結晶を用いて、従来よ
りもエネルギー分解能の良好な放射線検出素子を作製す
ることができるようになる。The present invention makes it possible to obtain crystals with high resistivity sufficient for producing radiation detection elements even when the chlorine concentration in the crystal is as low as 0.8 ppm to 5 ppm by weight. Became. Therefore, using this crystal, it becomes possible to produce a radiation detection element with better energy resolution than before.
第１図は熱処理温度による抵抗率の変化を示したもので
ある。
第２図は結晶中の塩素濃度と熱処理によって得られた抵
抗率の関係を示したものである。
第３図は結晶中の塩素濃度とキャリアライフタイムの関
係を示したものである。FIG. 1 shows the change in resistivity depending on the heat treatment temperature. FIG. 2 shows the relationship between the chlorine concentration in the crystal and the resistivity obtained by heat treatment. FIG. 3 shows the relationship between the chlorine concentration in the crystal and the carrier lifetime.
Claims (1)
おいて、塩素を０．８重量ｐｐｍ以上５重量ｐｐｍ以下
の濃度で添加したＣｄＴｅ単結晶を、真空中、あるいは
不活性ガス中で３５０℃以上４５０℃以下の温度で熱処
理することを特徴とするＣｄＴｅ単結晶の製造方法。(1) In a method for producing a CdTe single crystal for a radiation detection element, a CdTe single crystal to which chlorine is added at a concentration of 0.8 ppm to 5 ppm by weight is heated at 350°C or higher in vacuum or in an inert gas. A method for producing a CdTe single crystal, characterized by heat treatment at a temperature of 450° C. or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2210276A JPH0791155B2 (en) | 1990-08-10 | 1990-08-10 | Method for producing CdTe single crystal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2210276A JPH0791155B2 (en) | 1990-08-10 | 1990-08-10 | Method for producing CdTe single crystal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0497990A true JPH0497990A (en) | 1992-03-30 |
| JPH0791155B2 JPH0791155B2 (en) | 1995-10-04 |
Family
ID=16586712
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2210276A Expired - Lifetime JPH0791155B2 (en) | 1990-08-10 | 1990-08-10 | Method for producing CdTe single crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0791155B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0627506A1 (en) * | 1993-06-04 | 1994-12-07 | Japan Energy Corporation | CdTe crystal for use in radiation detector and method of manufacturing such CdTe crystal |
-
1990
- 1990-08-10 JP JP2210276A patent/JPH0791155B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0627506A1 (en) * | 1993-06-04 | 1994-12-07 | Japan Energy Corporation | CdTe crystal for use in radiation detector and method of manufacturing such CdTe crystal |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0791155B2 (en) | 1995-10-04 |
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