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In this paper we explain how to use rate equations to describe a laser that includes integrated optical feedback. We find a relation between the threshold current, the voltage drop at the gain section, output power, linewidth, and side mode suppression ratio, and show experimental results. [ABSTRACT FROM AUTHOR]

The double-capping procedure has been widely used to control the size distribution of self-assembled InAs/InGaAsP quantum dots during the growth on a (001) InP substrate. However, the conventional simulation method referred to one-step model does not include this procedure, which may lead to inaccuracy in modeling of quantum dots. An accurate method of modeling a single quantum dot including a thorough elastic strain analysis is proposed and developed in this paper. The confinement potential profiles are found significantly different between the two models. A series of settings (i.e., dot heights, dot base sizes, and dot shapes) is considered. The electronic band structure is calculated by using the eight-band $k \cdot p$ model. By comparing with the photoluminescence measurements in previously published works, it is found that the obtained optical transition energies using the accurate two-step model are in better agreement. The bright exciton splitting is found larger in terms of fine structures. Moreover, the impact of the quaternary compositions (arsenic mole fraction) of barrier material is for the first time systematically studied by using this accurate model. [ABSTRACT FROM AUTHOR]

The Coulomb exchange interaction can not only provide an exchange potential (real part), but also can generate optical polarization dephasing (imaginary part). Based on the density matrix as well as the electron scattering theory, in this paper, we reveal the relationship between the exact exchange potential and the exchange-induced dephasing time in quantum plasmonics. Our results indicate that the linewidth of the nanoplasmonics is mainly determined by a first-order Coulomb interaction in the Hartree–Fock approximation rather than a second-order (or high-order) interaction. Meanwhile, the exact exchange potential, a long-term problem to use this nonlocal functional in practical system for huge computation, can be calculated from the corresponding simple damping factor with great efficiency. In addition, since the Coulomb screening effect is automatically included, this relation provides a new thought to detect and test how the nonlocal exchange functions are related to the density-dependent screening Coulomb effect, hence the development of the density functional theory in chemistry and condensed matter physics. Finally, numerical simulations demonstrate that our model can reveal more quantum phenomena than traditional methods in nanoplasmonics, and these quantum features are consistent with the results obtained from the first principles. [ABSTRACT FROM AUTHOR]

In this paper, the two-step mesas of quasi-vertical GaN p-i-n diodes grown on pattern sapphire substrates (PSSs) with a 3- \mu \textm~i -layer were defined by two-step dry etching to different depths to prevent the effects of sidewall damages. As compared with the one-step mesa device, the two-step mesa devices show lower reverse leakage currents, lower capacitances, lower specific ON-resistances, and higher reverse breakdown voltages. Furthermore, one of the two-step mesa devices with plasma treatment exhibits about two orders of magnitude of reduction in the leakage current at −100 V, a breakdown voltage of 495 V, and a specific ON-resistance ( \textR\rm{\scriptscriptstyle ON}\vphantom {\sum ^{R^R}}\text{A} ) of 0.27 \textm\Omega -cm ^ 2 . Baliga’s figures of merit ( \textV B^ 2/\textR\rm{\scriptscriptstyle ON}\vphantom {\sum RR_R}\text{A} ) of 0.908 GW/cm ^ 2 , which is the highest value reported for the fabricated GaN p-i-n diodes grown on sapphire, is achieved for the GaN p-i-n diode grown on PSS with a two-step mesa and plasma treatment. [ABSTRACT FROM PUBLISHER]

This paper reports a solution-based method for the application of multiple nanostructures on full surface of GZO/GaN-based LEDs to enhance light-extraction efficiency. Ga-doped ZnO (GZO) was deposited to a thickness of 1μm and an n+-InGaN/GaN short-period superlattice structure was grown to improve the electrical characteristics of the LEDs, including series resistance and operating voltage. A solution-based method was used to control the density of ZnO nanoparticles deposited on the SiO2 layer for use as self-assembled etching nanomasks. Multiple nanostructures were simultaneously formed on the surfaces of GZO, p-GaN, and n-GaN by dry etching. The proposed LEDs increase light output power by 10%-27% (at 20 mA) over that of regular GaN-based LEDs. The difference in light output power can be attributed to differences in the shape, thickness, and density of GZO and GaN nanostructures, resulting in a reduction in Fresnel reflection provided by the roughened surface of the GaN-based LEDs. [ABSTRACT FROM AUTHOR]