When measuring radiation with very low intensity, it is important that the detector has the largest possible detection area and the largest possible volume. The larger the area and volume of the detector, the more particles are captured and the faster the necessary data is obtained. On the other hand, with increasing area and volume of the detector, the noise also increases, which considerably limits the use of the detector.
The quality of the detector depends very much on the quality (purity) of the semiconductor substrate.