LYNRED is oriented towards excellence in II-VI, III-V and bolometers technologies, covering all Society’s needs in term of infrared detection. Our vision is to preserve and protect, and more than ever, our goal is to provide the right technology to the field missions, spatial and industrial applications, and more generally the right technology to customers’ needs. For this purpose we are developing for the next generation pitch, MCT HOT technology, for extended MW band as well as III-V HOT MW blue band technology. Many challenges have to be addressed for future small pitch, large format and HOT detectors. Electrical and optical crosstalks as well as image quality and stability, are one of the prime concern for detectors with pixel pitch below 10μm. We will discuss about the trade-off between the different material properties and detector performances to ensure mandatory minimization of Minimum Resolvable Temperature Difference (MRTD) for range optimization. We will then review latest 7.5μm pitch development at LYNRED, with SXGA formats, based on II-VI and III-V HOT materials, in terms of operability, residual fixed pattern noise (RFPN) and Modulation Transfer Function (MTF) optimizations.
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%.
This work reports remanent electric-control of spin-orbit torques (SOT) in a perpendicular ferromagnet-SrTiO3 system. Non-volatile electric-control of the sheet resistance is achieved with 1150% contrast, and two remanent resistivity states. A remanent electric-control of the SOT efficiency is demonstrated using second harmonic Hall methods, with sign inversion of the anti-damping-like effective field. These results are consistent with a combination of both intrinsic modulation of the SOT efficiency and extrinsic modulation due to the non-volatile electric-control of the current injection in the 2DEG. The non-volatile control of the SOT effective field is evidenced by reproducible inversion of the SOTs after voltage pulses initialization, opening the way to reconfigurable SOT memories and logic-gate architectures.
Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced, bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI.
We show that both the amplitude and sign of this BMR can be tuned by controling, with an electric gate, the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1 % and has a larger figure of merit than previously measured TIs.
We propose a theoretical model giving a quantitative account of our experimental data.
This phenomenon, unique to TI, offer novel opportunities to tune the electrical response of surface states for spintronics.
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