Counterfeit electronics are a growing problem for the electronic information industry worldwide, so developing unbreakable security tags is crucial to ensure the trustworthiness and traceability of electronics. Traditional anticounterfeiting and trace solutions rely on reproducible deterministic processes and additional labels, which can still be copied or faked by counterfeiters. Herein, physical unclonable functions enabled by spontaneously formed plasmonic core–shell nanoparticles on electrodes are proposed to ensure label‐free traceable electronics, giving a practical solution to fight against counterfeit electronics. Random hemispherical core–shell nanoparticles are intentionally introduced on the metal electrode of different semiconductors (Si, GaAs, and GaN) from Ni/Au bilayer heterofilms by rapid thermal annealing, which can be integrated with electronics seamlessly, with no negative effect on electrical properties. The position, size, and shape of nanoparticles are random and uncontrollable; the corresponding scattering patterns, intensity, and spectra can work as nanofingerprints of the electrode, proving multidimensional unclonable labels with large encoding capacity suitable for electrodes smaller than several micrometers. It can be further combined with machine vision and artificial intelligence to identify and track electronics automatically and efficiently. The anticounterfeiting electrodes also show good thermal robustness and mechanical stability, opening up a prospect for practical anticounterfeiting of electronics.

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The increasing security threat is a serious challenge to the internet of things (IoT). Hardware‐based security primitive is an essential and powerful way to protect IoT devices from various attacks. But most of the current security hardwares are based on macrophysical features, which are usually produced by reproducible deterministic processes and can be copied by counterfeiters. Herein, a physical unclonable function (PUF) with high robustness based on the intrinsic random micro‐/nanostructures of the electronic packages is proposed thereby demonstrating a low‐cost and label‐free hardware security solution for IoT. Using the unique surface micropattern and the spatially coded laser scattering, the proposed PUFs can be used as anticounterfeiting labels, authentication tokens and cryptographic key generators. With the help of the proposed PUFs, the safety protection is still effective even when the attacker is able to get access to the database because the secret keys are inherently hidden in the complex microscopic stochastic physical features of the PUFs but not the database. The proposed package‐enabled PUFs provide a promising and practical physical protection solution for IoT security.

material systems such as wide tunable direct bandgap, inherent fast carrier dynamics, fast carrier transport, high breakdown fields, robust antiirradiation, and strong chemical stability, RTDs based on III-nitride are expected to provide better tunability of resonant tunneling compared with conventional material platforms such as AlGaInAs and AlGaInSb. [1][2][3][4][5][6] Besides, III-nitride materials are characterized by their large longitudinal optical (LO) phonon energies, making them promising candidates for room temperature terahertz quantum cascade lasers (THz-QCLs). [7] As the simplest quantum device adopting resonant tunneling, RTDs form the fundamental background to understand the quantum confinement and vertical transport processes in nitride-based supperlattices, an essential forestep for the realization of III-nitride-based THz-QCLs and quantum cascade detectors. [8][9][10] However, the demonstration of resonant tunneling in III-nitrides remained a challenge until recently. Due to high dislocation densities in heteroepitaxial GaN templates/buffer layers, current-voltage (I-V) behaviors in earlier reports exhibited noteworthy impact from trap states depending on scan directions and times, where the occurrences of negative differential resistance (NDR) were accidental, irreproducible and could not be easily correlated with resonant tunneling. [11][12][13][14][15][16][17][18][19] Demonstrations of clear and repeatable NDR from resonant tunneling in III-nitride based RTDs have been limited to those grown on high quality freestanding (FS) GaN substrates, i.e., through homoepitaxy, with either lowaluminum content AlGaN barriers measured at cryogenic temperature, or AlN barriers measured at room temperature. [20][21][22][23][24] Several motivations exist to grow RTD on sapphire substrates. First, sapphire substrates are more cost-friendly and easier to realize large-size wafer as well as mass production, and could directly lead to a monolithic integration of RTDs with the increasingly sophisticated high frequency devices fabricated on sapphire and even silicon substrates. Second, unlike FS GaN substrates which are usually n-type without intentionally doping, sapphire substrates are inherently insulating, very Resonant tunneling diodes (RTDs) are candidates for high power terahertz oscillators, and form the basis for understanding the quantum confinement and vertical transport in quantum structures such as quantum cascade lasers and quantum cascade detectors. In this work, repeatable negative differential resistance (NDR) is achieved in AlN/GaN RTDs grown on sapphire substrate by plasma-assisted molecular-beam epitaxy. Two reproducible NDR regions sequentially following two preresonance replicas are demonstrated at room temperature. A current region exhibiting negative correlation with temperature and oscillation-like features is first identified under reverse bias, which is interpreted as a combined contribution of weak resonant tunneling channels through different bound states in the well. The revealed peak...