Let us introduce you
So you’ve never heard of CZT? Or you want to find out a bit more about this nifty bit of physics?
You’ve come to the right place!
CZT, which stands for Cadmium Zinc Telluride, is a small semiconductor that is utilized across a range of applications, one of which being radiation detection here at kromek. Semiconductors, although not as conductive as metals, can still conduct electricity in specific conditions or circumstances. For instance, CZT can operate very effectively at room temperature due to its low conductivity, much lower than other semiconductors such as silicon or germanium.
So what exactly is going on here!?
In summary, how CZT detects radiation is by converting x-rays or gamma photons into a flow of charge. The energy of the radiation released is proportional to the charge generated in the detector. The readout electronics convert the charge into a voltage pulse and these voltage signals can be used to plot individual peaks in a spectrum so the isotope(s) present in the radioactive source can be identified.
Pretty sophisticated, right?
If you really want to get into the nitty gritty of CZT, the whole process of how it works can be broken down into several steps in more detail:
Yeah, the science is cool, but what are the benefits?
The high resolution of CZT-based detectors significantly outperforms any commercially available scintillators. This because scintillators are light-based meaning they convert radiation energy in light rather than electricity. The much higher resolution of CZT enables more distinguished spectral peaks to be plotted for more accurate isotope identification and analysis.
CZT is no one trick pony; it can be cut and shaped into an array of different sizes for specific solutions across multiple applications such as medical, industrial, security and research. For example, thicker cuts are more effective for use in instances involving higher energy photons e.g. at the site of nuclear accidents.
Now this is what sets CZT apart from the rest
As mentioned previously, CZT can operate at room temperature, without the need for cooling. And this is even with a processing power of >100 million photons s-1mm-2. Other semiconductors like germanium need to be cooled before use in field, costing time, energy and money.
This is not all! CZT has a much higher average atomic number than other semiconductors like silicon or germanium. As a result, CZT has a higher sensitivity for medium and high energy photons. This is particularly significant in medical fields of Advanced Imaging, as it helps produce more accurate results to increase confidence in diagnoses e.g. early detection of breast cancer, cardiac conditions and osteoporosis.
CZT enables lower doses of radiation to be exposed to patients undergoing diagnostic tests. This is because CZT is much more efficient than other semiconductors at detecting incoming flux of photons (especially higher energy ones) which have passed through a patient. As these photons carry diagnostic information, it means that less radiation is exposed to the patient in order to obtain diagnostic images, all the while the clinical value of the test remains as good as before, or even better.
Furthermore, compared to large and fragile germanium-based detectors, the small size and durability of CZT also makes it highly portable and cost-effective, suited for use in both the lab and field. Save your energy and your money!
And here’s the evidence! The performance of CZT-based detectors compared to germanium-based detectors was investigated by Sara Vichi and their team back in 2016. Watch out germanium, you’ve got competition!