Enhanced radial growth of Mg doped GaN nanorods: A combined experiment and first-principles based analysis

氧掺杂ZnO纳米棒中的激子开关与可调激子-声子耦合

Exciton switching and tunable exciton-phonon coupling in Oxygen doped ZnO nanorods

通过氧离子辐照调控ZnO纳米棒缺陷，实现可逆激子开关及激子-声子耦合的调谐，为缺陷可编程纳米光子器件提供新途径。

State-of-the-art and prospects for intense red radiation from core-shell InGaN/GaN nanorods

Core-shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) are promising for monolithic white light-emitting diodes and multicolor displays. Such applications, however, are still a challenge because intensity of red band is too weak as compared with blue and green ones. To clarify the problem, we have performed power and temperature dependent, as well as time-resolved measurements of photoluminescence (PL) in NRs of different In content and diameter. These studies have shown that the dominant PL bands originate from nonpolar and semipolar QWs, while a broad yellow-red band arises mostly from…

Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography

Rare-earth phosphors exhibit unique luminescence polarization features originating from the anisotropic symmetry of the emitter ion's chemical environment. However, to take advantage of this peculiar property, it is necessary to control and measure the ensemble orientation of the host particles with a high degree of precision. Here, we show a methodology to obtain the photoluminescence polarization of Eu-doped LaPO4 nano rods assembled in an electrically modulated liquid-crystalline phase. We measure Eu3+ emission spectra for the three main optimal configurations (σ, π and α, depending on the …

Nitrogenated CQD decorated ZnO nanorods towards rapid photodegradation of rhodamine B: a combined experimental and theoretical approach

In this work, hybridization of nonmetal nitrogen-doped carbon dots (NCQDs) with ZnO nanorods (NRs) is utilized towards better photocatalytic degradation of rhodamine B under ultraviolet (UV) irradiation. The structural characterization is confirmed by XRD, XPS, FTIR and HRTEM measurements, while, optical properties have been investigated using UV-visible absorbance spectroscopy and photoluminescence study. The dye degradation using ZnO NR is recorded as ~69%, while the performance of ZnO/NCQD climbs up to ~90%, after nine minutes of UV irradiation. Furthermore, the reusability test suggests be…

Electron Mobility in Polarization-doped Al$\mathrm{_{0-0.2}}$GaN with a Low Concentration Near 10$\mathrm{^{17}}$ cm$\mathrm{^{-3}}$

In this letter, carrier transport in graded Al$\mathrm{_x}$Ga$\mathrm{_{1-x}}$N with a polarization-induced n-type doping as low as ~ 10$\mathrm{^{17}}$ cm$\mathrm{^{-3}}$ is reported. The graded Al$\mathrm{_x}$Ga$\mathrm{_{1-x}}$N is grown by metal organic chemical vapor deposition on a sapphire substrate and a uniform n-type doping without any intentional doping is realized by linearly varying the Al composition from 0% to 20% over a thickness of 600 nm. A compensating center concentration of ~10$\mathrm{^{17}}$ cm$\mathrm{^{-3}}$ was also estimated. A peak mobility of 900 cm$\mathrm{^2}$/V$…

Study of two-subband population in Fe-doped AlxGa1-xN/GaN heterostructures by persistent photoconductivity effect

The electronic properties of Fe-doped Al0.31Ga0.69N/GaN heterostructures have been studied by Shubnikov-de Haas measurement. Two subbands of the two-dimensional electron gas in the hetero-interface were populated. After the low temperature illumination, the electron density increases from 11.99 x 1012 cm-2 to 13.40 x 1012 cm-2 for the first subband and from 0.66 x 1012 cm-2 to 0.94 x 1012 cm-2 for the second subband. The persistent photoconductivity effect (~13% increase) is mostly attributed to the Fe-related deep-donor level in GaN layer. The second subband starts to populate when the first …

关于Mg掺杂N极GaN中载流子损失的起源

On the Origin of Carrier Loss in Mg-Doped N-Polar GaN

研究发现Mg掺杂N极GaN中载流子损失主要由中性$(V_N-3Mg_{Ga})^0$复合物的形成引起。

体AlN衬底上相干应变AlN/GaN/AlN量子阱中的Shubnikov-de Haas振荡

Shubnikov-de Haas oscillations in coherently strained AlN/GaN/AlN quantum wells on bulk AlN substrates

该研究在体AlN衬底上的相干应变AlN/GaN/AlN量子阱中观察到SdH振荡，揭示了未掺杂与δ掺杂结构的能带占据差异，并直接测量了2DEG关键参数，为氮化物异质结构设计提供基础。

Controlling a three dimensional electron slab of graded Al$_{x}$Ga$_{1-x}$N

Polarization induced degenerate $n$-type doping with electron concentrations up to $\sim$10$^{20}$\,cm$^{-3}$ is achieved in graded Al$_{x}$Ga$_{1-x}$N layers ($x$: 0\%$\rightarrow$37\%) grown on unintentionally doped and on $n$-doped GaN:Si buffer/reservoir layers by metal organic vapor phase epitaxy. High resolution x-ray diffraction, transmission electron microscopy and electron energy loss spectroscopy confirm the gradient in the composition of the Al$_{x}$Ga$_{1-x}$N layers, while magnetotransport studies reveal the formation of a three dimensional electron slab, whose conductivity can be…

Enhanced magnetism of Cu$_n$ clusters capped with N and endohedrally doped with Cr

The focus of our work is on the production of highly magnetic materials out of Cu clusters. We have studied the relative effects of N-capping as well as N mono-doping on the structural stability and electronic properties of the small Cu clusters using first principles density functional theory based electronic structure calculations. We find that the N-capped clusters are more promising in producing giant magnetic moments, such as 14 $μ_B$ for the Cu$_6$N$_6$ cluster and 29 $μ_B$ for the icosahedral Cu$_{13}$N$_{12}$ clusters. This is accompanied by a substantial enhancement in their stability…

Ultrathin GaN Nanowires: Electronic, Thermal, and Thermoelectric Properties

We present a comprehensive computational study of the electronic, thermal, and thermoelectric (TE) properties of gallium nitride nanowires (NWs) over a wide range of thicknesses (3--9 nm), doping densities ($10^{18}$--$10^{20}$ cm$^{-3}$), and temperatures (300--1000 K). We calculate the low-field electron mobility based on ensemble Monte Carlo transport simulation coupled with a self-consistent solution of the Poisson and Schrödinger equations. We use the relaxation-time approximation and a Poisson-Schrodinger solver to calculate the electron Seebeck coefficient and thermal conductivity. Latt…