Optical imaging of growth defects in infrared crystals

Abstract This paper describes the use of two recently developed and commercially available infrared optical imaging systems for studying growth defects in several important semiconductor crystals such as CdGeAs 2 and Tl 3 AsSe 3 . The systems were used in a mode where transmitted illumination rather than black body radiation was imaged. One type of system utilizing an IR-sensitive vidicon is sensitive to 2.0 μm. The other, using either an InSb or a HgCdTe photodetector is sensitive in the 2–5.6 μm and the 8–14 μm range. With standard macro lens systems, both were capable of resolving millimeter and sub-millimeter growth defects such as internal cracks, voids, and precipitates.