SnS has recently been shown to possess unique valleytronic capability with large polarization degree, where non-degenerate valleys can be accessed using linearly polarized light, bestowed upon by the unique anisotropy and wavefunction symmetry. It is thus of utmost importance to demonstrate the extension of such effects for the IV-VI system in general, thereby elucidating the generality and tunability of such valleytronics. We show the highly tunable valleytronics via gradual compositional control of the Tin(II) Sulfo-Selenide (SnSxSe1-x) alloy system with excellent retainment of symmetry-determined selection rules. We show the presence of both ΓY and ΓX valleys in all alloy compositions via selectivity in absorption and emission of linearly polarized light by optical reflection (R)/transmission (T) and photoluminescence (PL) measurements, and tuned the bandgaps of the valleys within a range of 1.28eV to 1.05eV and 1.48eV to 1.24eV respectively. This simultaneous tuning of non-degenerate valleys agrees well with theoretical calculations. We then fitted the bandgap values in compositional space, obtaining the bowing parameters as a useful database. We further demonstrated the feasibility of using IV-VI valleytronics systems in general by elucidating the retainment of strong polarization degrees of as high as 91% across all compositions. The generalization of such purely symmetry-dependent valleytronics also opens up opportunities for discovery of more multi-functional materials.

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Physical unclonable function (PUF) is a promising hardware security primitive that can be applied to various security related areas. The ring oscillator (RO) PUF is one of the most popular PUFs that can generate the volatile key by comparing the frequency between ROs. Previous RO PUFs incur unacceptable hardware overheads to improve the reliability in order to eliminate the effect of environment factors. In this paper, we propose a frequency offset algorithm (FOA) to enhance the reliability and low the hardware overhead. The key idea is to make the frequency difference larger than a given threshold by offsetting the frequencies of RO pairs. Experimental results show that our proposed FOA method has the better reliability and lower hardware overhead than the temperatureaware cooperative (TAC). Especially, our proposed method can achieve the 100% utilization of ROs.