Green electroluminescence (EL) from silicon-based devices is achieved by precisely regulating the structure of Ga2O3/Al2O3:Tb nanolaminates using atomic layer deposition. The inherent negative charges, which originate primarily from oxygen vacancies and are more abundant in Ga2O3 than in Al2O3, are proved to be partially compensated by the Ga2O3-Al2O3 interfaces. This phenomenon enables a favorable balance between effective carrier injection and high excitation efficiency. The optimal Ga2O3/Al2O3:Tb EL device, annealed at 650 degrees C with Ga2O3 and Al2O3 sublayers of comparable thickness, exhibits the emission intensity of 1.22 mW/cm2 and the external quantum efficiency of 5.14%. The tolerance to injection current and the operation time of the Ga2O3/ Al2O3:Tb devices could be improved by three orders of magnitude when the nanolaminates are predominantly composed of Ga2O3 content, at the expense of reduced EL intensity and lower excitation efficiency. This work explores the modulation mechanism and intrinsic factors enabling the strong and stable EL from rare earth-doped oxide nanolaminates.

Based on previous achievement in the fabrication of silicon-based perovskite MgGeO3 and olivine Mg2GeO4 nanofilms using atomic layer deposition, the electroluminescence (EL) properties of these matrices doped with Er3+ ions are explored. The dopant Er2O3 atomic layers influence the growth of MgO/GeO2 nanolaminates, as evidenced by the increased Mg/Ge ratio and the difference in resultant lattice structure. Er3+ ions are proven to preferentially occupy the octahedral sites, thereby increases octahedron/tetrahedron ratio in the lattice and are conducive to the formation of the Mg2GeO4 structure. The perovskite MgGeO3 is superior to olivine Mg2GeO4 as the EL matrix, the electrical injection and excitation efficiency of perovskite MgGeO3:Er nanofilms are significantly higher than olivine Mg2GeO4:Er ones. Adjusting the matrix recipes using different Mg/Ge ratios or MgO cycles in each supercycle also yields the above-mentioned EL difference that determined by the lattice structure. The EL device using amorphous MgGeO3:Er nanofilm achieves a high external quantum efficiency of 20.9% and a power density of 7.88 mW cm(-2), and could operate for up to 2.43 & times; 10(4) s. This work explicates the importance of precisely control of the components in MgO/GeO2/Er2O3 nanolaminates for achieving efficient EL from perovskite MgGeO3:Er nanofilms, and demonstrates their potential applications in silicon-compatible optoelectronics.

The silicon-based olivine Mg2GeO4 and perovskite MgGeO3 nanofilms with good crystallinity and morphology are fabricated by atomic layer deposition of the MgO/GeO2 nanolaminates. The growth of GeO2 on MgO and oppositely, the growth of MgO on GeO2, are both certified to exhibit the loss of growth thickness and produce Mg-Ge compounds, while the loss of GeO2 is more significant in the former case, ascribing to the island growth mode of MgO and the subsequent penetrating growth of GeO2 in the nanolaminates. The recipe using 10 MgO cycles in each supercycle with the nominal Mg/Ga ratio of >= 1.67 is required for the deposition of olivine Mg2GeO4 and the threshold crystalline temperature is 900 degrees C. In comparison, the perovskite MgGeO3 nanofilms require the recipe using 5 MgO cycles, the nominal Mg/Ge ratio of <= 1.67, and the threshold crystalline temperature of 800 degrees C. The perovskite MgGeO3 nanofilms exhibit larger nanograins with smoother morphology in comparison to the olivine Mg2GeO4 nanofilms. Deviation from the stoichiometric Mg/Ge ratios in the recipes results in the nanofilms with pinholes or restricted crystallinity. This work explores the fabrication parameters for the specific lattice structures from MgO/GeO2 nanolaminates, and demonstrates their potential for the silicon-compatible electronic and photonic applications.

The engineering of surficial ligands plays a crucial role in the optoelectronic performance of perovskite quantum dot light-emitting diodes (PQD-LEDs). In this work, via a ligand exchange strategy using diisooctylphosphinic acid (DOPA), which exhibits stronger bonding capacity with component Pb2+ ions, the surface ligands of FA0.15Cs0.85PbBr3 PQDs are optimized, beneficial for both radiative recombination and operational stability. The green PQD-LED (peaking at 520 nm) achieves a maximum luminance of 1.337 × 105 cd m-2, with an external excitation efficiency of 16.88%, and a long operational lifetime (T50) of 4.31 h at a high luminous of 1000 cd m-2. The restriction of Br- ion migration in PQDs, by using DOPA ligands to alter the surficial species and lattice components, results in stable emission peaks that are independent of bias voltage and operation time. This method is widely applicable for fabricating optoelectronic devices using PQDs with mixed components to improve efficiency and stability.

In pursuit of better electroluminescence (EL) performance from Er-doped MgGaxAlyO4:Er (MGAO:Er) spinel nanofilms, multiple Al2O3 nanolayers are inserted into the Ga2O3/MgO/Er2O3 nanolaminates by atomic layer deposition. The Al2O3 interlayers result in a higher crystallization temperature, while the changes in lattice constant and binding energy verify the finite substitution of Ga by Al ions in spinel lattice by inserting sufficient Al2O3 nanolayers. The comparison confirms the difference in crystallization due to the intact Al2O3 nanolayers, rather than the change in inversion degree of spinel lattice, results in the different EL spectra. The EL excitation efficiency of the optimal device (4 Al2O3 nanolayers, 700 degrees C-annealed) reaches 4.5 %, with the maximum emission intensity of 14.5 mW cm(-2). The EL devices based on MGAO:Er nanofilms annealed at 600-700 degrees C exhibit significantly improved operation stability, the device utilizing appropriate Al2O3 interlayers (4 layers in a similar to 80 nm film) achieves the stable operation during continuous electrical injection for more than 10 days, benefiting from the quasi-crystalline structure and smooth morphology of the MGAO:Er spinel nanofilms. This work further reveals the changes in lattice crystallinity by the regulation of component and annealing temperature of oxide nanolaminates, and contributes to the silicon-based optoelectronic application of artificially designed nanofilms.

For silicon-based devices using dielectric oxides doped with rare earth ions, their electroluminescence (EL) performance relies on the sufficient carrier injection. In this work, the atomic Ga2O3 layers are inserted within the Er-doped GeO2 nanofilms fabricated by atomic layer deposition (ALD). Both Ga(CH3)3 and Ga(C2H5)3 could realize the ALD growth of Ga2O3 onto the as-deposited GeO2 nanofilm with unaffected deposition rates. The interfacial defects introduced by atomic Ga2O3 layers decrease the threshold voltage while increasing the tolerable injection current of the EL devices; the 1530 nm emissions from the 600 °C-annealed Ga2O3/GeO2:Er nanolaminate devices achieve the optical power density of 16.2 mW/cm2, with the excitation efficiency increased to 12.5%. Moreover, the interface modification by atomic Ga2O3 layers significantly prolongs the operation time of these prototype devices, reaching 5.21 × 104 s for the optimal one. High-temperature annealing above 800 °C results in the decomposition of GeO2 and leaves reticular porous nanofilms. The conduction mode within these amorphous Ga2O3/GeO2:Er nanolaminates conforms to the trap-assisted tunneling mechanism, with the depths of defect states lowered by the interfacial Ga2O3 layers. These Ga2O3/GeO2:Er nanolaminates with improved EL performance demonstrate new potential in the utilization of ALD GeO2 nanofilms in silicon-compatible optoelectronics.

The Ga2O3/MgO/Er2O3 nanolaminates are fabricated by atomic layer deposition and crystallized into Er-doped MgGa2O4 spinel (MGS:Er) nanofilms after annealing, with their electroluminescence (EL) performance characterized. The annealing above 600 degrees C achieves the polycrystalline spinel nanofilm, and the crystallization is promoted by the higher annealing temperature and Ga2O3/MgO ratio. The dopant Er3+ ions preferably substitute into the octahedron sites occupied by Ga3+ ions in ordinary spinel and Mg2+ in anti-spinel lattice, while the inversion degree is confirmed to increase with the reduction of Ga2O3/MgO ratio and annealing temperature, resulting the relatively enhanced secondary EL at 1542 nm. This perturbation by Er3+-substitution into antispinel sites improves the emission intensity and excitation efficiencies, the main EL emission peaking at 1531 nm from the optimal MGS:Er device exhibits the excitation efficiency reaching 5.8 %, with the enhanced electrical injection realizing the maximum EL intensity above 17.3 mW/cm2. The fluorescence lifetime of these MGS: Er devices is established in the range of 371-760 mu s, which decreases mainly with the Er concentrations. The prototype device using the near-stoichiometric Ga2O3/MgO ratio shows the operation time of 1.12 x 105 s. This work explores the fabrication of Si-based spinel nanofilms with designed composition and special microstructure, and their practical application in optoelectronics.

Based on previous results of the Er-doped GeO2 nanofilms fabricated by atomic layer deposition (ALD), the interfacial reactions of Al2O3 precursor within the GeO2/Al2O3:Er nanolaminates are investigated. The ALD pulse of Al(CH3)3 etches the as-deposited GeO2 nanofilm, while the oxidation of Al(CH3)3 by ozone realizes the deposition of atomic Al2O3 layer onto GeO2 surface. The Al2O3 atomic layers with >= 4 ALD cycles improve the thermal stability of the ALD GeO2 nanofilms, which restrain the formation of nanograins and also the reduction of film thickness during high-temperature annealing, giving rise to smooth GeO2/Al2O3:Er nanolaminates. For the 1530 nm electroluminescence (EL) from the silicon-based devices fabricated using the GeO2/Al2O3:Er nanolaminates annealed at 800 degrees C, the excitation efficiency is tripled to 22.1 %. The conduction of the energetic electrons resulting in the EL emissions still confirms to the trap-assisted tunneling mechanism within these amorphous GeO2/Al2O3:Er nanolaminates. The prototype devices based on the Al2O3-inserted nanolaminates exhibit comparatively increased operation time. These GeO2/Al2O3:Er nanolaminates with enhanced stability and improved optoelectronics performance pave the way for the practical utilization of ALD GeO2 nanofilms.

Er3+-doped polycrystalline MgAl2O4 (MAO:Er) spinel nanofilms are deposited via atomic layer deposition, and the metal-oxide-semiconductor light emitting devices are fabricated. The crystallinity and morphology of the MAO:Er nanofilms are explored by modifying the annealing temperatures, Al2O3/MgO ratios and Er2O3 dopant cycles. The similar electroluminescence (EL) emissions peaking at 1530 nm indicates the identical crystal field environment for the doped Er3+ ions. The concentration quenching is verified to occurs via the energy transfer among the neighboring Er3+ ions. The optimal device (800 degrees C-annealed, Al2O3/MgO ratio close to stoichiometry, Er3+: 1.85 mol%) yields the highest external quantum efficiency of 28%, the power efficiency of 0.32% and the optical power density of 14.62 mW cm(-2). The smooth MAO:Er spinel nanofilms with the low refractive index and high resistance ensure the highly efficient light extraction and the generation of energetic electrons for the impact excitation of Er3+ ions. The trap-assisted tunneling under operation electric field dominates the conduction mechanism for the EL emissions. The estimated decay lifetime of 1154.4 mu s and a large-stimulated emission cross-section in the order of 10(-15)-10(-14) cm(2) are revealed from the EL emissions. Intense near-infrared emissions from these Si-based MAO:Er devices have great potential in the optoelectronic applications.

Bright white emission is obtained under electrical excitation from dysprosium doped Y3Ga5O12 garnet (YGG:Dy) nanofilms fabricated by atomic layer deposition on silicon substrates. Electroluminescence (EL) composed of yellow (580 nm) and blue (482 and 492 nm) emission corresponds to the CIE chromaticity coordinates of (0.3568, 0.3807) and a CCT of ∼4700 K and can be used for lighting and displays. The crystallization and micro-morphology of polycrystalline YGG:Dy nanolaminates are explored by adjusting the annealing temperature, Y/Ga ratio, Ga2O3 interlayer thickness and Dy2O3 dopant cycle. The near-stoichiometric device annealed at 1000 °C presents optimal EL performance with the maximum external quantum efficiency and the optical power density reaching 6.35% and 18.13 mW cm-2, respectively. The EL decay time is estimated to be 273.05 μs, with a large excitation section of 8.33 × 10-15 cm2. The conduction mechanism is confirmed to be the Poole-Frenkel mode under operation electric fields and the impact-excitation of Dy3+ ions by energetic electrons results in emission. Bright white emission from Si-based YGG:Dy devices can provide a new route to developing integrated light sources and display applications.

Y0.9(GdxBi1−x)0.1BO3 phosphors (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0, YGB) were obtained via high-temperature solid-state synthesis. Differentiated phases and micro-morphologies were determined by adjusting the synthesis temperature and the activator content of Gd3+ ions, verifying the hexagonal phase with an average size of ~200 nm. Strong photon emissions were revealed under both ultraviolet and visible radiation, and the effectiveness of energy transfer from Bi3+ to Gd3+ ions was confirmed to improve the narrow-band ultraviolet-B (UVB) (6PJ→8S7/2) emission of Gd3+ ions. The optimal emission was obtained from Y0.9Gd0.08Bi0.02BO3 phosphor annealed at 800 °C, for which maximum quantum yields (QYs) can reach 24.75% and 1.33% under 273 nm and 532 nm excitations, respectively. The optimal QY from the Gd3+-Bi3+ co-doped YGB phosphor is 75 times the single Gd3+-doped one, illustrating that these UVB luminescent phosphors based on co-doped YBO3 orthoborates possess bright UVB emissions and good excitability under the excitation of different wavelengths. Efficient photon conversion and intense UVB emissions indicate that the multifunctional Gd3+-Bi3+ co-doped YBO3 orthoborate is a potential candidate for skin treatment.

Polycrystalline erbium-doped Y3(AlxGa1-x)5O12 (Er-YAGG) nanofilms with various Al/Ga compositions are deposited on silicon using atomic layer deposition followed by annealing at different temperatures. The Al/Ga ratios and the corresponding annealing temperatures required for crystallization are confirmed by investigating the diffraction patterns and micro-morphologies. The co-alloying of Al and Ga compositions controllably changes the lattice constant and impacts the grain growth. The crystal-field splitting of doped Er3+ ions is also modified, manifesting different electroluminescence (EL) spectra that also indicate the crystallization of garnet matrices. The EL performance of a device based on the Y3Al2Ga3O12 nanofilm (1.39 at% Er dopant) annealed at 900 °C is improved due to the adjustment of morphology and microstructural perturbations that are beneficial for radiative transition. The optimal EL device exhibits a low onset voltage of ∼25 V and a maximum external quantum efficiency of 3.29%. The excitation cross-section under electrical pumping is estimated to be 1.18 × 10-15 cm2. The carrier transport of these co-alloyed Er-YAGG devices conforms to the Poole-Frenkel mechanism. Both the EL decay lifetime and the device operation time increase with the incorporation of Ga within the Er-YAGG nanofilms. These Er-YAGG devices with tunable optoelectronic properties manifest promising potential for the engineering of light sources compatible with CMOS technology.

Er-doped Lu3Ga5O12 garnet(LuGG:Er)nanofilms are obtained by the crystallization of Lu2O3/Er2O3/Ga2O3 nanolaminatesfabricated using atomic layer deposition on silicon. The temperaturerequired for garnet crystallization is independent of the Lu/Ga ratiosand the interlayer thickness in the nanolaminates, and a thresholdtemperature of 800 & DEG;C is identified, ascribing to the easiermigration and reconstruction of the gallium component. The efficienciesand lifetime of the characteristic 1.53 & mu;m electroluminescence(EL) from Er3+ ions within polycrystalline LuGG:Er nanofilmsare correlated with the Lu/Ga ratios, and a higher doping concentrationof 3.5 mol % is preferable. The optimal device exhibits an externalquantum efficiency of 2.5% and a power efficiency of 5.2 x 10(-4), with the maximum optical power density reaching4.9 mW/cm(2) and the fluorescence lifetime longer than 2ms. The electron injection within the LuGG:Er devices follows thetrap-assisted tunneling mechanism under the operating electric field,resulting in the impact excitation of Er3+ ions. The prototypeLuGG:Er device operates stably for & SIM;9.2 h while maintaining90% of the initial EL intensity. This work further explores the depositionof compound oxide nanofilms with controlled composition and crystallinityat low temperature and Si-based garnet nanofilms for the optoelectronicapplications.

Er-doped GeO2 (GeO2:Er) nanofilms are fabricated by atomic layer deposition on silicon, from which the 1530 nm electroluminescence (EL) is achieved. The GeO2:Er nanofilms maintain the amorphous structure after annealing at 600-1000 degrees C, while the annealing above 800 degrees C results in the loss of Ge due to the volatile GeOx (x < 2) species. These GeO2:Er nanofilms could withstand the wet lithography process and the prototype devices could operate under the constant current. The 650 degrees C annealed GeO2:Er devices manifest the threshold of similar to 40 V and 10(-7) A, while the maximum injection current is 0.28 A/cm(2). The EL power density from the device doped with 3.09 mol% Er reaches to 2.2 mW/cm(2), with the external quantum efficiency of 7.3% and power efficiency of 0.17%. The conduction mechanism for the excitation of Er emission confirms to the trap-assisted tunneling mode within the amorphous GeO2:Er nanolaminates. This work demonstrates the potential of GeO2:Er nanofilms in the utilization of Si-based optoelectronics.

Amorphous Al2O3-Y2O3:Er nanolaminate films are fabricated on silicon by atomic layer deposition, and ~1530 nm electroluminescence (EL) is obtained from the metal-oxide-semiconductor light-emitting devices based on these nanofilms. The introduction of Y2O3 into Al2O3 reduces the electric field for Er excitation and the EL performance is significantly enhanced, while the electron injection of devices and the radiative recombination of doped Er3+ ions are not impacted. The 0.2 nm Y2O3 cladding layers for Er3+ ions increase the external quantum efficiency from ~3% to 8.7% and the power efficiency is increased by nearly one order of magnitude to 0.12%. The EL is ascribed to the impact excitation of Er3+ ions by hot electrons, which stem from Poole-Frenkel conduction mechanism under sufficient voltage within the Al2O3-Y2O3 matrix.

Polycrystalline erbium-doped Y3Ga5O12 garnet (YGG) nanofilms are deposited by atomic layer deposition on Si substrates after annealing down to 800 °C, based on which ∼1.53 μm electroluminescence (EL) devices are fabricated. The optimal EL performance depends on the adjustment of Y/Ga ratio and Ga2O3 interlayer thickness within the nanolaminates, which exert no prominent impact on the crystallization and film morphology of YGG nanofilms. EL spectra reveal that the crystalline structure after annealing impacts the surrounding environment of Er3+ ions, leading to different emission peaks. These silicon-based devices present a low turn-on voltage of ∼25 V, while the external quantum efficiency and maximum optical power density reach 2.51% and 10.03 mW cm-2, respectively. The EL is ascribed to the impact-excitation of doped Er3+ ions in polycrystalline YGG nanofilms by energetic electrons, the conduction mechanism of which is confirmed to be the Poole-Frenkel mode. These prototype devices possess excellent stability and can operate for up to 49 hours under continuous current injection, verifying the improvement of device performance by the utilization of gallium in the fabrication of garnet nanofilms. The Si-based YGG:Er EL devices are of promising potential for integrated optoelectronic applications.

Near-infrared electroluminescence (EL) peaking at 1067 nm is achieved from the devices based on Ga2O3:Nd nanolaminates fabricated by atomic layer deposition on silicon. The emissions originating from intra-4f transitions in Nd3+ ions are activated by both forward and reverse biases, with an external quantum efficiency of similar to 1% and the optical power density of 10.5 mW/cm2. The devices operate continuously for more than 4 h and exhibit fluctuant EL emission under alternating-current excitation. Such EL is triggered by the energetic electrons accelerated via interfacial SiOx or Al2O3/ TiO2 nanolaminate layers. EL under unidirectional bias is obtained by using a 4 nm interfacial Al2O3 nanofilm that sustains the electric field and energizes injected electrons, demonstrating the acceleration of electrons by high resistance layers and the carrier conduction considering interface energy barrier is indispensable for efficient EL excitation. This work provides innovative nanofilms based on Nd-doped oxides with great potential for applications in Si-based photonics and integrated optoelectronics.

Numerical simulations are carried out to study the effects of aerosol particles acted as cloud condensation nuclei (CCN) and ice nuclei (IN) on thunderstorm properties. A two-cylinder time-dependent cloud and aerosol interaction model with the spectral bin microphysical parameteri-zation, explicit noninductive electrification and lightning process is utilized to explore the im-pacts. This model not only uses the high-resolution particle size bins to describe the distributions of aerosol particles and hydrometeors, but also can be applied to study the diffusional growth of aerosol particles to cloud droplets and to track the mass of both CCN and IN in hydrometeors. The simulated cloud properties show that increased CCN concentrations result in more numerous but smaller droplets and form ice particles less efficiently, producing less numbers of graupel and less efficient conversion to raindrops. Increased IN concentrations directly enhance the heterogeneous nucleation, and then boost the subsequent microphysical processes, contributing to the produc-tion of increasingly numbers of graupel which eventually pass through the melting layer and then enhance the precipitation. As CCN concentrations increase, the charge density gained by different mass-binned ice particles and total charge density significantly decrease due to reduced large ice particles with greater diameters than 360 mu m. In contrast, as IN concentrations are further increased, dramatically increased large ice particles with greater diameters than 360 mu m are produced and thus, support the enhanced charge density gained by different mass-binned ice particles and total charge density. Besides, as expected, the reduced (enhanced) lightning fre-quency is well explained by the reduced (increased) numbers of large ice particles (diame-ter>360 mu m).

Er-doped Gd2O3/Ga2O3 nanolaminates are fabricated by atomic layer deposition on silicon, which transform to polycrystalline Gd3Ga5O12 garnet (GGG) nanofilms after annealing above 900 degrees C. The Gd/Ga ratio approaching stoichiometry and Ga2O3 interlayers thinner than 1.5 nm are essential for the gallium garnet crystallization after annealing, while resulting in better film morphology in optoelectronic utilization, otherwise the Ga2O3 interlayers tend to segregate into micrometer grains on the surface. The impact-excitation of the doped Er3+ ions by hot electrons within the nanolaminate GGG:Er devices results in the characteristic Er3+ electroluminescence (EL) centered at 1530 nm, exhibiting the external quantum efficiency of 1.9% and decay lifetime of 1.27-2.47 ms. Stronger EL emissions and longer lifetime are obtained from the devices with the stoichiometry Gd/Ga ratio and better morphology. The electron conduction within the GGG matrix is ascribed to the trap-assisted tunneling mechanism above threshold electric field. This work further explores the deposition of nanolaminates with designed component and crystallinity, and the possibility of fabricating optoelectronic devices from Si-based garnet nanofilms.

Förster resonant energy transfer between atoms separated at a distance of a few nanometers has strong relevance to different properties of matter. In this work, the resonant energy transfer rate is derived from the electric potential in a system with one dipole interacting with a separated 2D plane of dipoles. It shows an R-2 (R: distance between dipole and 2D plane of dipoles) dependency on the distance of dipole layers, which is different from previous theoretical evaluations with an R-4 dependency. The electroluminescence (EL) properties are studied in different rare earth (Re: Tm, Tb, Ho, Yb, Er) distributed single atomic layer doped Al2O3 nanolaminates prepared by atomic layer deposition, in which the distance between single atomic layers of Re3+ is modulated at the atomic scale. Our theoretical results are consistent with the changes of EL intensity and decay time with the distance between the single atomic rare earth doping layers. This result is crucial for increasing the accuracy in biosensing and design of photonic materials.