Accurate Nonlocal Impact Ionization Models for Conventional and Staircase Avalanche Photodiodes Derived by Full Band Monte Carlo Transport Simulations

Pilotto, A.; Esseni, D.; Selmi, L.; Palestri, Pierpaolo

doi:10.1109/jqe.2022.3200728

Cited by 2 publications

(1 citation statement)

References 40 publications

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“…History dependence can be introduced in the carrier branching process in APDs, thus increasing determinism, which further decreases the ENF below 2. ,,− After an ionization event occurs, each carrier needs to travel a minimum distance, which is frequently referred to as the “dead space/length,” before it can gain sufficient energy from the electric field to have a nonnegligible ionization probability. When the thickness of the multiplication region becomes comparable to a “few” dead spaces/lengths, the nonlocal/non-Markovian history-dependent effects dominate .…”

Section: Introductionmentioning

confidence: 99%

Non-Markovian Hole Excess Noise in Avalanche Amorphous Selenium Thin Films

Mukherjee

Han

et al. 2023

ACS Omega

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Enhancing the signal-to-noise ratio in avalanche photodiodes by utilizing impact ionization gain requires materials exhibiting low excess noise factors. Amorphous selenium (a-Se) as a wide bandgap at ∼2.1 eV, a solid-state avalanche layer, demonstrates single-carrier hole impact ionization gain and manifests ultralow thermal generation rates. A comprehensive study of the history dependent and non-Markovian nature of hot hole transport in a-Se was modeled using a Monte Carlo (MC) random walk of single hole free flights, interrupted by instantaneous phonon, disorder, hole−dipole, and impact-ionization scattering interactions. The hole excess noise factors were simulated for 0.1−15 μm a-Se thin-films as a function of mean avalanche gain. The hole excess noise factors in a-Se decreases with an increase in electric field, impact ionization gain, and device thickness. The history dependent nature of branching of holes is explained using a Gaussian avalanche threshold distance distribution and the dead space distance, which increases determinism in the stochastic impact ionization process. An ultralow non-Markovian excess noise factor of ∼1 was simulated for 100 nm a-Se thin films corresponding to avalanche gains of 1000. Future detector designs can utilize the nonlocal/non-Markovian nature of the hole avalanche in a-Se, to enable a true solid-state photomultiplier with noiseless gain.

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