Zhiyuan Yu

Xi’an Institute of Optics and Precision Mechanics of Sciences

Silicon sub-bandgap near-infrared (NIR) (λ > 1100 nm) photovoltaic (PV) response by plasmon-enhanced internal pho-toemission was investigated. The Si sub-bandgap NIR PV response, which remains unexploited in Schottky junction-like solar cell device, was examined using nanometer sized Au/Al 2 O 3 /n-Si junction arrays. This kind of metal-insulator-s...

Localized surface plasmon resonances (LSPRs) in metallic nanostructures attract great attention for their potential applications such as highly sensitive optical sensors. However, the performance of LSPR sensors is strongly hampered by their low quality (Q) factors due to the intrinsic ohmic losses and far‐field radiation losses. Here, a kind of al...

Direct-band silicon materials have been a sought-after material for potential applications in silicon photonics and solar cells. Accordingly, methodologies like nanostructure engineering, alloy engineering and strain engineering have been developed. In this work, the particle swarm optimization (PSO) algorithm is used to design direct-band Si-Ge al...

Electrically pumped distributed feedback (DFB) lasing in silicon nanocrystals (SiNCs) has been observed. The DFB SiNC laser was made based on a SiNC light-emitting diode (LED) by incorporating a second-order DFB grating. The light emission covered the visible regime. Optical gains in the order of 10² cm⁻¹ were found in the light emitting regime. Th...

A luminescent Si nanocrystal (SiNC) thin film with photoluminescence quantum yield (PLQY) >70% was made by using hydrogen silsesquioxane (HSQ), followed by long-time high-pressure hydrogenation. A net optical gain of 524±21 cm⁻¹ was obtained by means of variable stripe length-shifting excitation spot (VSL-SES). A rectangularly shaped SiO2 Fabry-Per...

The electronic structures and optical properties of novel 2D biphenylene and hydrogen-terminated nanoribbons of different widths which are cut from a layer of biphenylene were explored via first-principles calculations. The findings of phonon computations demonstrate that such a biphenylene is dynamically stable and shows metallic properties. The c...

A synergistic approach of interface engineering is reported to efficiently improve the performance of silicon nanocrystal light-emitting diode (Si-NC LED). This approach employs electron transport layer (ETL) of n-type gallium-nitride (n-GaN) and hole transport layer (HTL) of alumina (Al2O3) to improve the charge injection and transport during the...

High brightness Si nanocrystal white light-emitting diodes (WLED) based on differentially passivated silicon nanocrystals (SiNCs) are reported. The active layer was made by mixing freestanding SiNCs with hydrogen silsesquioxane, followed by annealing at moderately high temperatures, which finally led to a continuous spectral light emission covering...

Freestanding silicon nanocrystals (SiNCs) were prepared based on triethoxysilane (TES) by a series processes of chemistry and physics. To prevent self-aggregation, the freestanding SiNCs were mixed with 1-dodecene and mesitylene, followed by addition reaction in argon. A dispersed freestanding SiNC colloid was thus attained. A Si white light-emitti...

Though photoluminescence (PL) of Si quantum dots (QDs) has been known for decades and both theoretical and experimental studies have been extensive, their luminescence mechanism has not been elaborated. Several models have been proposed to explain the mechanism. A deep insight into the origin of light emissions in Si QDs is necessary. This work cal...

Photoluminescence (PL) enhancement of Si nanocrystals (Si-NCs) embedded in SiO2 matrix by high-pressure (30 bar) Ar passivation at moderately high temperatures has been observed. For the same pressure, time and temperature of passivation, the PL enhancement of Si-NCs for the Ar passivated sample is even larger than that for the regular H2 passivate...

Electronic properties of monolayer tellurium (Te) with three proposed atomic configurations under external electric field were investigated through first-principles calculations. The calculated results demonstrate that α-Te and γ-Te have indirect band gaps, whereas β-Te, when no electric field is applied, can be considered as a direct semiconductor...