Role of the Metal-Semiconductor Interface in Halide Perovskite Devices for Radiation Photon Counting.
Shreetu ShresthaHsinhan TsaiMichael YohoDibyajyoti GhoshFangze LiuYusheng LeiJeremy TisdaleJon BaldwinSheng XuAmanda J NeukirchSergei TretiakDuc VoWanyi NiePublished in: ACS applied materials & interfaces (2020)
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.
Keyphrases
- solid state
- monte carlo
- solar cells
- living cells
- room temperature
- high resolution
- healthcare
- fluorescent probe
- heavy metals
- molecular dynamics
- risk assessment
- computed tomography
- molecular dynamics simulations
- peripheral blood
- magnetic resonance imaging
- density functional theory
- magnetic resonance
- human health
- single cell
- ionic liquid
- climate change
- health risk
- radiation induced