Illumination Induced Negative Differential Resistance in InGaAs Avalanche Photodiode

This work presents a novel InGaAs/InP avalanche photodiode, fabricated in the separate absorption, grading, charge, and multiplication configuration operated at non-cryogenic conditions under low-frequency ramp gating. An optimized three stage InP multiplication layer of
$1\mu m$
thickness offers an extended linear mode operation by reducing the punch-through voltage, and indefinitely increasing the avalanche threshold voltage. A large background dark current is observed following steady, and linear multiplication in approximately direct relationship with the ramp gating. For 1310 nm short-wave infrared, normal incidence pulsed illumination at instant-to-peak voltage ratios of
$(0.11,0.2,0.6, 0.89, 0.98, 0.9)$
, a sort of negative differential resistance is incorporated into the device in a qualitative sense, owing to the illumination induced switching/variations in the intrinsic values of electron, and hole avalanche coefficients in the multiplication region. Under fixed illumination, an interesting deduction from the transient photo response is the slow quenching phenomenon prolonging
$\sim 120 \mu s$
for all the electrical field establishments in the device. The related measurement scheme paves the way for futuristic ramp-driven InGaAs/InP APDs for detecting SWIR wavelengths under required low power consumption environments.