MCT p-on-n photodiodes manufactured at Lynred and CEA-LETI have demonstrated state of the art performances for HOT applications. On blue and red mid infrared bands on 15μm pixel pitch, respectively 150 and 130K operating temperatures have been obtained, due to diffusion limited dark current and low defectivity. To achieve equivalent results on smaller pixel, the p-on-n technology at DEFIR, joint laboratory between Lynred and CEA-LETI, has been improved. The technological process was modified to ensure a proper diode formation and to efficiently passivate the interface between MCT and encapsulation layers, especially in the vicinity of the space charge region. The manufactured arrays with a 5.3μm cutoff wavelength have been hybridized on a digital output SXGA (1280×1024) direct injection ROIC with a pixel pitch of 7.5 μm. This paper present the measured current, blackbody responsivity and RMS noise on FPAs with F/4 numerical aperture. We will also discuss spectral response, quantum efficiency, shot-noise limited photodiodes and noise histograms shapes and their distribution tails at 130K. The very low number of defective pixel allow to address higher operating temperature and measurements have been performed at 140K and even 150K with very limited performance degradation. Pixel pitch of 5 μm has been characterized on test chips and present I-V curves with low dispersion and long bias plateau. As for larger pixel sizes, these photodiodes are shot-noise limited. Modulation transfer function has been measured by electron beam induced current and presents high value, up to 56%.
One limitation of dark current for HOT HgCdTe MWIR detector is diffusion current related to Auger generation mechanisms. However, this limit can be overcame using a fully depleted P-i-N diode structure. On the way toward PIN structures, we discuss on the impact of Auger suppression on partially fully-depleted photodiodes. Indeed, we report dark current evolution with temperature following a diffusion trend line but also a dark current decreasing when increasing the applied voltage in the temperature range 120-180K on the same detector. If the SRH current in the space charge region is very low, an Auger suppression mechanism should result in a decrease of the total dark current when depleting a larger volume of the pixel on such detector. This hypothesis could match with the reported dark current data obtained on detectors manufactured at CEA LETI and Lynred. They are based on p/n diodes, 7.5μm pitch arrays connected as 2x2 super-pixels to a 15μm pitch ROIC (640x512 VGA format).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.