Search

This work demonstrates quasi-vertical GaN Schottky barrier diodes (SBDs) on 6-inch Si substrate with a breakdown voltage (BV) over 1 kV, the highest BV reported in vertical GaN-on-Si SBDs to date. The deep mesa inherently in quasi-vertical devices is leveraged to form a self-aligned edge termination, and the mesa sidewall is covered by the p-type nickel oxide (NiO) as a reduced surface field (RESURF) structure. This novel termination enables a parallel-plane junction electric field of 2.8 MV/cm. The device also shows low turn-on voltage of 0.5 V, and low specific on-resistance of 1.1 m ·cm2. Moreover, the device exhibits excellent overvoltage robustness under the continuous 800 V stress in the unclamped inductive switching test. These results show the good promise of the low-cost vertical GaN-on-Si power diodes.

Measurements of quantum states of photons are conventionally performed with series of optical elements in bulk setups [1] or optical chips incorporating multiple tunable beam splitters. Here, we suggest and develop experimentally, for the first time to our knowledge, a new concept of quantum-polarization measurements with a single all-dielectric resonant metasurface [2]. The operating principle is presented in Fig. 1(a): A metasurface spatially splits different components of photon polarization states, which then enables full reconstruction of the photon state based on the photon correlations with simple polarization-insensitive single-photon detectors or EMCCD cameras. The subwavelength thin structure provides an ultimate miniaturization, and can facilitate quantum tomography by spatially-resolved imaging without a need for reconfiguration. Such parallel-detection approach promises not only better robustness and scalability, but also the possibility to study the dynamics of quantum states in real-time.

Metasurfaces are ultra-thin patterned structures that emerged recently as planar metadevices [1] capable of reshaping and controlling incident light. Many designs and functionalities of metasurfaces suggested so far, are based largely on plasmonic planar structures, however most of these metasurfaces demonstrate low efficiencies in transmission due to losses in their metallic components. In contrast, all-dielectric resonant nanophotonic structures [2] avoid absorption losses, and can drastically enhance the overall efficiency [3-5], especially in the transmission regime. Recently we have seen a number of demonstrations of all-dielectric metasurfaces with ever-increasing transmission efficiency in both near infrared and visible spectral range. This makes dielectric metasurfaces a promising novel platform for flat optical devices such as waveplates, Q-plates, lenses, and holograms.