Role of the Metal-Semiconductor Interface in Halide Perovskite Devices for Radiation Photon Counting
Makaleler > Tam Makale · 2020
Yazarlar: Shreetu Shrestha, Hsinhan Tsai, Mıchael Duncan YOHO, Dibyajyoti Ghosh, Fangze Liu, Yusheng Lei, Jeremy Tisdale, Jon Baldwin, Sheng Xu, Amanda J. Neukirch, Sergei Tretiak, Duc Vo, Wanyi Nie
ACS Applied Materials and Interfaces, SCI Expanded İndekslerine Giren Dergi, Uluslararası, Scopus, 2020, cilt 12, ss 45533-45540
Özet
Halide perovskites are promising optoelectronic semiconductors. For applications in solid-state detectors that operate in low photon flux counting mode, blocking interfaces are essential to minimize the dark current noise. Here, we investigate the interface between methylammonium lead tri-iodide (MAPbI3) single crystals and commonly used high and low work function metals to achieve photon counting capabilities in a solid-state detector. Using scanning photocurrent microscopy, we observe a large Schottky barrier at the MAPbI3/Pb interface, which efficiently blocks dark current. Moreover, the shape of the photocurrent profile indicates that the MAPbI3 single-crystal surface has a deep fermi level close to that of Au. Rationalized by first-principle calculations, we attribute this observation to the defects due to excess iodine on the surface underpinning emergence of deep band-edge states. The photocurrent decay profile yields a charge carrier diffusion length of 10-25 μm. Using this knowledge, we demonstrate a single-crystal MAPbI3 detector that can count single γ-ray photons by producing sharp electrical pulses with a fast rise time of <2 μs. Our study indicates that the interface plays a crucial role in solid-state detectors operating in photon counting mode.