RESUMEN
We performed a systematic study involving simulation and experimental techniques to develop induced-junction silicon photodetectors passivated with thermally grown SiO2 and plasma-enhanced chemical vapor deposited (PECVD) SiNx thin films that show a record high quantum efficiency. We investigated PECVD SiNx passivation and optimized the film deposition conditions to minimize the recombination losses at the silicon-dielectric interface as well as optical losses. Depositions with varied process parameters were carried out on test samples, followed by measurements of minority carrier lifetime, fixed charge density, and optical absorbance and reflectance. Subsequently, the surface recombination velocity, which is the limiting factor for internal quantum deficiency (IQD), was obtained for different film depositions via 2D simulations where the measured effective lifetime, fixed charge density, and substrate parameters were used as input. The quantum deficiency of induced-junction photodiodes that would be fabricated with a surface passivation of given characteristics was then estimated using improved 3D simulation models. A batch of induced-junction photodiodes was fabricated based on the passivation optimizations performed on test samples and predictions of simulations. Photodiodes passivated with PECVD SiNx film as well as with a stack of thermally grown SiO2 and PECVD SiNx films were fabricated. The photodiodes were assembled as light-trap detector with 7-reflections and their efficiency was tested with respect to a reference Predictable Quantum Efficient Detector (PQED) of known external quantum deficiency. The preliminary measurement results show that PQEDs based on our improved photodiodes passivated with stack of SiO2/SiNx have negligible quantum deficiencies with IQDs down to 1 ppm within 30 ppm measurement uncertainty.
RESUMEN
We demonstrate the use of a dual-mode detector for determining the internal quantum deficiency of a silicon photodiode without the use of an external reference. This is achieved by combining two different principles for measuring optical power in one device, where the photodiode is used as absorber for both thermal and photon detection. Thermal detection is obtained by the same principle as for an electrical substitution radiometer (ESR), with a type A measurement uncertainty of 0.34 % in unstabilized room temperature. The optical power measured in thermal mode was around 3 % ± 0.5 % higher than what was measured in photocurrent mode. Heat transfer simulations revealed a difference of up to 2.2 % between optical and electrical heating, and based on these simulations we give recommendations for improvements of the detector thermal design.
RESUMEN
Spectrally invariant detectors are commonly used to interpolate or extrapolate the responsivity of InGaAs detectors in the infrared from absolute calibrations at a few wavelengths. The random noise in such detectors limits the accuracy that can be achieved in a narrowband, double-monochromator setup. We propose the application of a dedicated digital filter, which reduces the uncertainty by 30%, and combine it by calibrating a group of three detectors. The uncertainties are propagated from the observed variance in the relative measurement to the combined uncertainty of 0.4% (2sigma) in the responsivity values of the InGaAs detectors in the range of 1010-1640 nm.