A few years ago, CZT detectors made by eV Products showed up in quantity on eBay. Pretty much everyone interested in radioactivity seemed to snap one up back then. It took a fairly long time for folks to figure out how to use them well! But they're really not bad, especially for the size.
This isn't much more than a factoid, but notice that many of the useful semiconductors are made from elements that straddle the column containing silicon and germanium. Making compounds whose outer shell electrons add up to be silicon-like lets you make semiconductors, but with electrical and optical properties that you can tune. GaAs is another one, and the LED's are made by choosing particular combinations that have specific bandgap energies corresponding to colors of photons.
Part of the "magic" involves finding ratios of elements that have relatively little mechanical strain, because the atoms "fit" just right, which introduce defects that degrade the semiconductor behavior.
Here's some spectra with 3% FWHM @ 662 keV:
https://maximus.energy/index.php/2020/05/01/gamma-spectrosco...
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