Phosphors for Radiation Detectors

6Semiconductor Scintillators

Naoki Kawano

Graduate School of Engineering Science, Akita University, Japan

6.1 Introduction

Semiconductor scintillators are phosphor materials, exploiting optical properties of semiconductors. Semiconductors include various materials such as IVB (C, Si, Ge, etc.), IVB–IVB (SiC, SiGe, etc.), IIIB–VB (GaAs, etc.), and IIB–VIB (ZnS, ZnSe, etc.). They are used in many applications such as light emitting diodes and laser diodes, as well as scintillators. The well‐known original semiconductor scintillator was the ZnS‐based phosphor materials reported around 1900, which emit scintillation photons where alpha and beta particles can be detected by naked eye [1]. Up to now, it has been demonstrated that various semiconductor scintillators such as Ga₂O₃ and Te‐doped CdS show bright scintillation with a short decay time. Many types of emissions from semiconductors under ionizing radiation are observed, depending on the chemical composition, band structure, and defective state. In this chapter, fundamental photoluminescence and scintillation mechanisms in semiconductors are first recapped, and the examples of the previously reported semiconductor scintillators are subsequently summarized (Table 6.1).

Table 6.1 Scintillation characteristics of various semiconductor scintillators.

Scintillator	Density g/cm3	Wavelength nm	Relative Intensity	Light yield(γ) photons/MeV	Light yield(α) photons/5.5 MeV‐α	Decay time ns	References
PbI2	6.2	~495/~510–530 ...