طراحی و ساخت آشکارساز نیم‌رسانای CdZnTe برای آشکارسازی پرتو گاما

نوع مقاله: مقاله پژوهشی

نویسندگان

مجتمع پژوهشی شمال غرب، پژوهشگاه علوم و فنون هسته‌ای، صندوق پستی: 836-14395، بناب ـ ایران

چکیده

در این مقاله، مرحله‌های انتخاب بلور، آماده‌سازی نمونه‌ها و نحوه‌ی ایجاد اتصال‌های شوتکی و اهمی برای ساخت آشکارساز CdZnT یا CZT قابل حمل و با قابلیت کار در دمای اتاق ارایه شده است. ابتدا درصد عناصر و اندازه‌های بلور CdZnTe با کد C4MCNP تعیین و تأثیر آن‌ها بر رفتار الکتریکی و آشکارسازی قطعه بررسی شد. پس از تهیه‌ی بلور، سطح بلور به روش شیمیایی آماده و فعال‌سازی شد. در طرف صاف‌تر سطح بلور، فلز طلا با خلوص بالا به ضخامت 100 نانومتر به عنوان اتصال شوتکی و بر روی طرف دیگر، فلز ایندیم به عنوان اتصال اهمی با روش تبخیر فیزیکی، لایه نشانی شد. مشخصات الکتریکی حسگر ساخته شده با استفاده از تجهیزهای دقیق اندازه‌گیری جریان ولتاژ، جریان- ظرفیت و
جریان- دما اندازه‌گیری و مشخصه‌های فیزیکی قطعه تعیین شد. در نهایت حسگر به پیش‌تقویت‌کننده، شکل‌دهنده‌ی تپ، تقویت‌کننده و تحلیل‌گر بس‌کاناله متصل شد. آشکارساز ساخته شده توسط چشمه‌های نقطه‌ای Cs137، Th232 آزموده شده و با نمونه‌هایی از اورانیم مقیاس‌بندی شد. نتیجه‌ها نشان داد که پهنای نیم- ارتفاع برای قله‌ی keV 662، برابر با %8/3 و خطای اندازه‌گیری برای نمونه‌های مجهول اورانیم کم‌تر از %3 است.
 

کلیدواژه‌ها


عنوان مقاله [English]

Design and manufacture of CdZnTe semiconductor detector for gamma ray detection

نویسندگان [English]

  • Navid Balkanian
  • Mikaeil Yeganeh
  • Shahriar Rahmatolapour
  • Mehdi Taghavi
  • Abolfazl Souri
چکیده [English]

In this paper, the process of crystal selection, samples preparation and method of shottkey and ohmic contacts creation for CdZnTe or CZT detector, to be used as a portable device operating at room temperature, have been reported. First, the ratio of CZT element and crystal dimensions was determined via MCNP4C code and its effect on the electrical and detection behavior was investigated. After the crystal preparation, its surface was activated by chemical method. On one side, Au with a thickness of 100nm was coated as a schottkey contact and on the other side, in was coated as an ohmic contact with physical vapor deposition. The electrical characters of the sensor such as current-voltage, current-capacitance and current-temperature were measured. The sensor was connected to a pre-amp, pulse shaping, amplifier and MCA. The detector was tested by point sources of Cs-137 and Th-232, and was calibrated by standard uranium samples. The results showed that the FWHM of 662 keV is 3.8 keV and the error for the enrichment determination was less than 3%.
 
 

کلیدواژه‌ها [English]

  • CZT crystal
  • Schottkey contact
  • Ohmic contact

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