Recent advances in avalanche photodiode technology

Avalanche photodiodes (APDs) are solid state devices having an internal signal gain which gives them a better signal-to-noise ratio than standard photodiodes. Also, their high quantum efficiency provides an advantage over photomultiplier tubes in some applications. Although they have been studied for years, recent advances in the fabrication techniques have allowed the construction of multielement arrays (up to 10 x 10) with high performance capability. This progress has resulted in increased potential for exploiting the advantages of APDs in a variety of research, industrial nondestructive testing, medical instrumentation, and biomedical research using low energy particles. For example, the direct detection of the distribution of tritium labeled, beta emitting compounds has been achieved. No other solid state detector is capable of doing this. Recent experimental data characterizing APDs and APD arrays used as x-ray, particle and low level light detectors are presented. In addition, their suitability in various applications is discussed