JPH0796478B2 - Method for producing CdTe single crystal - Google Patents
Method for producing CdTe single crystalInfo
- Publication number
- JPH0796478B2 JPH0796478B2 JP34940091A JP34940091A JPH0796478B2 JP H0796478 B2 JPH0796478 B2 JP H0796478B2 JP 34940091 A JP34940091 A JP 34940091A JP 34940091 A JP34940091 A JP 34940091A JP H0796478 B2 JPH0796478 B2 JP H0796478B2
- Authority
- JP
- Japan
- Prior art keywords
- single crystal
- crystal
- heat treatment
- temperature
- growth
- 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
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- Crystals, And After-Treatments Of Crystals (AREA)
- Measurement Of Radiation (AREA)
Description
【０００１】[0001]
【発明の技術分野】本発明は、放射線検出素子用等とし
て有用な高抵抗ＣｄＴｅ単結晶の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high resistance CdTe single crystal useful for a radiation detecting element or the like.
【０００２】[0002]
【従来技術】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−分解能化をめ
ざして、従来からその製造方法が検討されている。2. Description of the Related Art CdTe single crystals are useful for radiation detecting elements and the like, and their manufacturing methods have been studied in the past for the purpose of improving the characteristics thereof, and in particular, achieving higher energy resolution.
【０００３】高エネルギ−分解能を達成するための結晶
特性としては、主に次の２点が重要である。The following two points are mainly important as crystal characteristics for achieving high energy resolution.
【０００４】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、１×１０8Ωｃｍ以上の値が必要である。この抵
抗率を得るために、結晶中に１乃至１０ｐｐｍの微量の
塩素を添加し、３５０℃以上４５０℃以下の温度でこれ
を熱処理することが有効である。The first point is that the resistivity is high. A low resistivity undesirably increases the signal noise of the radiation detector and requires a value of 1 × 10 8 Ωcm or more. In order to obtain this resistivity, it is effective to add a minute amount of chlorine of 1 to 10 ppm into the crystal and heat-treat this at a temperature of 350 ° C. or higher and 450 ° C. or lower.
【０００５】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−分解能が低下する。キャ
リアライフタイムを増大するには結晶の純度を向上させ
ることが重要であり、このため、結晶の育成温度が低く
坩堝からの汚染を最小限に抑えられ、しかも、高純度化
の効果があるトラベリングヒ−タ−法（ＴＨＭ法）で結
晶を育成することが効果的である。The second point is that the carrier lifetime is large. When the carrier lifetime is short, the carrier collection efficiency is lowered and the energy resolution is lowered. In order to increase the carrier lifetime, it is important to improve the purity of the crystal. Therefore, the growth temperature of the crystal is low and the contamination from the crucible can be minimized. It is effective to grow crystals by a heater method (THM method).
【０００６】即ち、高エネルギ−分解能の素子を製造す
るには結晶中に１乃至１０ｐｐｍの微量の塩素を添加し
たＣｄＴｅ結晶をＴＨＭ法で製造し、それを３５０℃以
上４５０度以下の温度で熱処理した結晶を使用すること
が重要であった。That is, in order to manufacture a high energy-resolution element, a CdTe crystal in which a trace amount of chlorine of 1 to 10 ppm is added is manufactured by the THM method and heat-treated at a temperature of 350 ° C. or higher and 450 ° C. or lower. It was important to use the prepared crystals.
【０００７】[0007]
【本発明が解決する問題点】しかしながら、上記の方法
で製造した単結晶を使用して放射線検出素子を作成した
場合、育成したインゴットの成長方向長手の位置によっ
て、素子の性能が異なるという問題があった。即ち、長
さ１０ｃｍのインゴットでは、成長開始端から５ｃｍま
での成長開始部の結晶を使用して作製した０．２ｃｍ×
０．２ｃｍ×０．１２ｃｍの素子は241Ａｍの５９．５
ＫｅＶのエネルギ−を有する放射線に対するエネルギ−
分解能が５ＫｅＶを超えるものが多くなり、成長開始端
から５ｃｍ以降の成長終盤に育成された結晶を使用した
素子はエネルギ−分解能５ＫｅＶ以下の良好な素子が多
く得られる傾向があり、結果として、ＴＨＭ法で育成し
た１本の結晶インゴットから取れるエネルギ−分解能５
ＫｅＶ以下の優れた素子の歩留まりが３５％程度と低い
という問題点があった。However, when a radiation detecting element is produced using the single crystal produced by the above method, there is a problem that the element performance varies depending on the longitudinal position of the grown ingot in the growth direction. there were. That is, in the case of a 10 cm long ingot, 0.2 cm x produced by using the crystal of the growth start portion up to 5 cm from the growth start end.
A 0.2 cm x 0.12 cm element is 241 Am 59.5.
Energy for radiation having an energy of KeV
The resolution is more than 5 KeV in many cases, and the element using the crystal grown at the end of the growth of 5 cm from the growth start end tends to obtain many good elements with energy-resolution of 5 KeV or less. As a result, THM Energy obtained from a single crystal ingot grown by the method-resolution 5
There has been a problem that the yield of excellent elements of KeV or less is as low as 35%.
【０００８】本発明は、上記の問題点を解決したもので
あって、ＴＨＭ法で育成した１本の結晶インゴットから
歩留まり良くエネルギ−分解能５ＫｅＶ以下の優れた放
射線検出素子を得ることのできるＣｄＴｅ単結晶の製造
方法を提供するものである。The present invention has solved the above-mentioned problems, and a single crystal ingot grown by the THM method can be used to obtain an excellent radiation detection element having an energy resolution of 5 KeV or less with a good yield. A method for producing a crystal is provided.
【０００９】[0009]
【問題点を解決する手段および作用】すなわち、本発明
は、放射線検出素子用のＣｄＴｅ単結晶の製造方法にお
いて、塩素を添加したＣｄＴｅ単結晶を、５００℃以上
９００℃以下の温度で第１の熱処理を行なった後、３５
０℃以上４５０℃以下の温度で第２の熱処理を行なうこ
とを特徴とするＣｄＴｅ単結晶の製造方法を提供するも
のである。本発明者等は、ＴＨＭ法で長さが４ｃｍ以下
の短い単結晶を育成した場合、素子の性能が成長開始部
の単結晶も良好であることから、エネルギ−分解能が成
長方向長手に分布する原因が、結晶析出後に引き続き受
ける熱履歴の影響であると考え本発明に至ったものであ
る。即ち、ＴＨＭ法で長い単結晶を育成した場合、育成
炉の温度分布により、成長開始部の単結晶は、結晶析出
後に育成炉の低温部へ徐々に移動するため、低温で長時
間の熱履歴を受けることになる。本発明者等の単結晶育
成では、この熱履歴を受ける時間は約７００時間を超え
る。それに対して、成長終盤の単結晶は成長開始部の単
結晶に比べ、成長後に受ける低温での熱履歴の時間も少
ない。That is, the present invention provides a method for producing a CdTe single crystal for a radiation detecting element, wherein a chlorine-added CdTe single crystal is used as a first material at a temperature of 500 ° C. or higher and 900 ° C. or lower. 35 after heat treatment
The present invention provides a method for producing a CdTe single crystal, which comprises performing a second heat treatment at a temperature of 0 ° C or higher and 450 ° C or lower. The present inventors have found that when a short single crystal having a length of 4 cm or less is grown by the THM method, the element performance is good even for the single crystal at the growth start portion, so that the energy resolution is distributed in the longitudinal direction of the growth direction. The present invention is considered to be due to the influence of the thermal history that is continuously received after crystal precipitation, and the present invention has been achieved. That is, when a long single crystal is grown by the THM method, the single crystal at the growth start part gradually moves to the low temperature part of the growth furnace after crystal precipitation due to the temperature distribution of the growth furnace. Will be received. In the single crystal growth by the present inventors, the time for receiving this thermal history exceeds about 700 hours. On the other hand, the single crystal in the final stage of growth has a shorter thermal history at a low temperature after the growth than the single crystal in the growth start part.
【００１０】そこで、エネルギ−分解能低下の原因が、
結晶析出後に引き続き、低温で極めて長時間熱履歴を受
けるためであると考え、育成した結晶を５００℃以上９
００℃以下の温度域で熱処理することによって、この結
晶析出後の低温の熱履歴を消し去ることができると推定
し実験したところ、良好な結果が得られ本発明に至った
ものである。Therefore, the cause of the decrease in energy resolution is
It is thought that this is because, after the crystal precipitation, the crystal grown is subjected to a thermal history at a low temperature for an extremely long time, and the grown crystal is kept at 500 ° C. or higher for 9 hours or more.
It was estimated that it was possible to eliminate the low-temperature thermal history after crystal precipitation by heat treatment in the temperature range of 00 ° C. or lower, and an experiment was conducted. As a result, good results were obtained, which led to the present invention.
【００１１】本発明における第１の熱処理温度は５００
℃以上９００℃以下とされ、より好ましくは６００℃以
上８００℃以下とされる。熱処理温度が５００℃未満で
は結晶析出後の低温での熱履歴の影響を完全には消せ
ず、また、９００℃を超えると高蒸気圧成分であるＣｄ
が単結晶から抜けることにより放射線検出素子の性能の
低下が起こるからである。The first heat treatment temperature in the present invention is 500.
C. to 900.degree. C., more preferably 600.degree. C. to 800.degree. If the heat treatment temperature is lower than 500 ° C, the influence of the thermal history at a low temperature after crystal precipitation cannot be completely eliminated, and if it exceeds 900 ° C, the high vapor pressure component Cd
This is because the radiation of the radiation-detecting element deteriorates due to the removal of the single crystal from the single crystal.
【００１２】第２の熱処理温度は３５０℃以上４５０℃
以下とされ、より好ましくは３５０℃以上４００℃以下
とされる。３５０℃未満でも、４５０℃を超えても、抵
抗率は１×１０8Ωｃｍ以下となるからである。また、
塩素の添加量は１重量ｐｐｍ以上１０重量ｐｐｍ以下と
され、より好ましくは１．５重量ｐｐｍ以上３重量ｐｐ
ｍ以下とされる。The second heat treatment temperature is 350 ° C. or higher and 450 ° C.
Or less, and more preferably 350 ° C. or higher and 400 ° C. or lower. This is because the resistivity becomes 1 × 10 8 Ωcm or less at temperatures lower than 350 ° C. or higher than 450 ° C. Also,
The amount of chlorine added is from 1 to 10 ppm by weight, and more preferably from 1.5 to 3 ppm by weight.
m or less.
【００１３】[0013]
【実施例】ＴＨＭ法で育成した塩素濃度２重量ｐｐｍの
長さ１０ｃｍのＣｄＴｅ単結晶から結晶成長方向に等間
隔に４０枚のウエハ−を切り出し、石英アンプルに真空
封入し、７００℃で３時間、第１の熱処理をした後、１
０℃／時間で３８５℃まで降温し、さらにこの温度で１
８時間の第２の熱処理を行なった。第２の熱処理後、室
温まで４０℃／時間で降温した。[Example] 40 wafers were cut out from a CdTe single crystal having a chlorine concentration of 2 wtppm and a length of 10 cm grown by the THM method at equal intervals in the crystal growth direction, vacuum-sealed in a quartz ampoule, and kept at 700 ° C for 3 hours. , After the first heat treatment, 1
The temperature was lowered to 385 ° C at 0 ° C / hour, and then 1
A second heat treatment of 8 hours was performed. After the second heat treatment, the temperature was lowered to room temperature at 40 ° C./hour.
【００１４】この熱処理を行なった結晶を使用して各ウ
エハ−から約３０個ずつ放射線検出素子を作製した。Using this heat-treated crystal, about 30 radiation detecting elements were prepared from each wafer.
【００１５】次に、それぞれの素子について241Ａｍの
放射線（５９．５ｋｅＶのエネルギ−をもっている）に
対するエネルギ−分解能（ピ−ク強度半値幅）を測定し
た。その結果、成長開始部のウエハ−でも、エネルギ−
分解能が４ｋｅＶ以上５ｋｅＶ未満の素子が最も多く得
られ、全作製素子数に対する５ｋｅＶ未満の素子の割合
は８１％となり、高い歩留まりが得られた。Next, the energy resolution (peak intensity half width) for radiation of 241 Am (having an energy of 59.5 keV) was measured for each element. As a result, even in the wafer at the growth start portion, energy
The element with the resolution of 4 keV or more and less than 5 keV was obtained most, and the ratio of the element with less than 5 keV to the total number of fabricated elements was 81%, and a high yield was obtained.
【００１６】上記実施例では熱処理の雰囲気を真空とし
たが、Ａｒや窒素などの不活性ガス雰囲気としても同様
の効果が得られる。In the above embodiment, the heat treatment atmosphere is a vacuum, but the same effect can be obtained by using an inert gas atmosphere such as Ar or nitrogen.
【００１７】また、上記実施例では第１の熱処理に引き
続いて第２の熱処理を行なったが、第１の熱処理後いっ
たん室温まで冷却した後、第２の熱処理を行なっても同
様の効果が得られる。Although the second heat treatment is performed after the first heat treatment in the above embodiment, the same effect can be obtained by performing the second heat treatment after cooling to room temperature after the first heat treatment. To be
【００１８】さらに、上記実施例では第１の熱処理を単
結晶をウエハ−にしてから行なったが、インゴットのま
ま行なっても第２の熱処理をウエハ−にしてから行なえ
ば同様の効果が得られる。Further, in the above-mentioned embodiment, the first heat treatment is carried out after the single crystal is made into a wafer, but the same effect can be obtained if the second heat treatment is carried out even after carrying out the ingot as it is. .
【００１９】[0019]
【発明の効果】本発明により、ＴＨＭ法で作製したイン
ゴット全域からエネルギ−分解能５ＫｅＶ以下の良好な
放射線検出素子を歩留まり良く作製することができるよ
うになった。According to the present invention, it becomes possible to manufacture a good radiation detecting element having an energy resolution of 5 KeV or less from a whole area of an ingot manufactured by the THM method with a high yield.
Claims (1)
造方法において、塩素を添加したＣｄＴｅ単結晶を、５
００℃以上９００℃以下の温度で第１の熱処理を行なっ
た後、３５０℃以上４５０℃以下の温度で第２の熱処理
を行なうことを特徴とするＣｄＴｅ単結晶の製造方法。1. A method for producing a CdTe single crystal for a radiation detecting element, comprising:
A method for producing a CdTe single crystal, which comprises performing a first heat treatment at a temperature of 00 ° C. to 900 ° C. and then performing a second heat treatment at a temperature of 350 ° C. to 450 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34940091A JPH0796478B2 (en) | 1991-12-09 | 1991-12-09 | Method for producing CdTe single crystal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34940091A JPH0796478B2 (en) | 1991-12-09 | 1991-12-09 | Method for producing CdTe single crystal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05155699A JPH05155699A (en) | 1993-06-22 |
| JPH0796478B2 true JPH0796478B2 (en) | 1995-10-18 |
Family
ID=18403496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34940091A Expired - Fee Related JPH0796478B2 (en) | 1991-12-09 | 1991-12-09 | Method for producing CdTe single crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0796478B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7002230B2 (en) | 2003-02-07 | 2006-02-21 | Nikko Materials Co., Ltd. | CdTe-base compound semiconductor single crystal for electro-optic element |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06345598A (en) * | 1993-06-04 | 1994-12-20 | Japan Energy Corp | CdTe crystal for radiation detection element and manufacturing method thereof |
| JP4614616B2 (en) * | 2002-11-08 | 2011-01-19 | Ｊｘ日鉱日石金属株式会社 | ZnTe single crystal and method for producing the same |
| US8405037B2 (en) | 2008-02-12 | 2013-03-26 | Shimadzu Corporation | Radiation detector manufacturing method, a radiation detector, and a radiographic apparatus |
| JP6097854B2 (en) * | 2016-02-02 | 2017-03-15 | Ｊｘ金属株式会社 | Method for producing compound semiconductor crystal for radiation detection element |
| EP3923036A4 (en) | 2019-05-17 | 2022-11-02 | JX Nippon Mining & Metals Corporation | SEMICONDUCTOR WAFER, RADIATION DETECTION ELEMENT, RADIATION DETECTOR AND PRODUCTION METHOD FOR COMPOUND SEMICONDUCTOR SINGLE CRYSTALLINE SUBSTRATE |
| JP7250919B2 (en) | 2019-05-17 | 2023-04-03 | Ｊｘ金属株式会社 | Method for manufacturing semiconductor wafer, radiation detection element, radiation detector, and compound semiconductor single crystal substrate |
-
1991
- 1991-12-09 JP JP34940091A patent/JPH0796478B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7002230B2 (en) | 2003-02-07 | 2006-02-21 | Nikko Materials Co., Ltd. | CdTe-base compound semiconductor single crystal for electro-optic element |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05155699A (en) | 1993-06-22 |
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