Abstract
Polycrystalline PbSe for mid-wave infrared (IR) photodetectors is an attractive material option due to its high operating/ambient temperature operation and relatively easy and cheap fabrication process, making it a candidate for low-power, small footprint, uncooled/passively cooled photodetectors. However, there are many material challenges that reduce the specific detectivity (D*) of these detectors. In this work, we demonstrate that it is possible to improve upon this metric by externally modulating the effective lifetime of conducting carriers by application of a back-gate voltage that can control the recombination rate of carriers in the detector by increasing the passivation of PbSe. We build a back-gated PbSe detector, in which we experimentally observe unambiguous signature of effective carrier modulation with a back-gate voltage for different temperatures. We develop a quantitative model for the detector that captures and closely benchmarks this modulation, which is then used to project the increase in D* in better optimized detector designs. This approach when combined with other techniques, such as plasmonic enhancement of light absorption, can lead to substantive enhancement of performance in PbSe mid-wave IR detectors widening their application space.
Highlights
The mid-wave infrared (IR) atmospheric detection window (3 μm–8 μm of the EM spectrum) has been useful for applications in astronomy and earth sciences1,2 as well as military and surveillance.3 Integration of imaging sensors in commercial civilian applications, such as self-driving automotives,4 may expand the range of applications of such sensors manyfold
Better controlled fabrication protocols help in mitigating these issues to an extent; it is expedient to explore extrinsic electrical control that a read-out integrated circuit (ROIC) can provision to control these factors
The parameters Nb and tb can be obtained from imaging techniques, such as scanning electron microscopy, where average crystallite dimensions and inter-crystallite distances can be estimated. It can be seen from Eq (1) that the photo-generated carriers increase the conductivity of the film, and it presents a lower resistance that can be measured by the ROIC by measuring the RC delay of a network formed using the detector and a controlled capacitor
Summary
The mid-wave infrared (IR) atmospheric detection window (3 μm–8 μm of the EM spectrum) has been useful for applications in astronomy and earth sciences as well as military and surveillance. Integration of imaging sensors in commercial civilian applications, such as self-driving automotives, may expand the range of applications of such sensors manyfold. Integration of imaging sensors in commercial civilian applications, such as self-driving automotives, may expand the range of applications of such sensors manyfold These new classes of sensors will need to have high resolution and performance without active cooling to reduce energy and production cost and to increase compactness and integrability with other systems. PbSe is a century-old material that only has a niche market in mid-wave IR, compared to HgCdTe detectors, even though its cost of production is low and is integrable with a Si based read-out integrated circuit (ROIC).. PbSe is a century-old material that only has a niche market in mid-wave IR, compared to HgCdTe detectors, even though its cost of production is low and is integrable with a Si based read-out integrated circuit (ROIC).7 This is due to relatively lower performance and high pixel non-uniformity in a large focal plane array. We provide analysis of performance improvement exhibited by the experimental detector due to back-gate voltage and design optimizations that can translate the small signature of performance improvement in the experimental device into a substantial increase in well-designed detectors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
