Laser ultrasound detection by CdTe:V monopolar photo-EMF detector with responsivity close to theoretical limit

We report on the experimental demonstration of semiconductor photo-electromotive force (photo-EMF) adaptive detector for laser ultrasonic applications with responsivity close to the theoretical limit for monopolar device of this type. The photo-EMF detector fabricated of a monopolar CdTe:V crystal was characterized in the spectral region 827–852 nm which is very close to the fundamental optical absorption edge of CdTe ( ≈ 825 nm). At λ = 833 nm the experimentally observed photo-EMF signal amplitude reached its maximal value, which corresponds to the theoretical limit for a monopolar photoconductor with quantum efficiency of photoconductivity 0.6–0.75.