Hongping Zhao

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Strain-compensated InGaN–AlGaN quantum wells (QW) are investigated as improved active regions for lasers and light emitting diodes. The strain-compensated QW structure consists of thin tensile-strained AlGaN barriers surrounding the InGaN QW. The band structure was calculated by using a self-consistent 6-band formalism, taking into account valence band(More)
Improvement of light extraction efficiency of InGaN LEDs using colloidal-based SiO2 /polystyrene (PS) microlens arrays was demonstrated. The size effect of the SiO2 microspheres and the thickness effect of the PS layer on the light extraction efficiency of III-nitride LEDs were studied. The monolayer rapid convective deposition conditions forSiO2(More)
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Staggered InGaN quantum wells (QWs) are analyzed as improved active region for light-emitting diodes (LEDs) emitting at 500 nm and 540 nm, respectively. The calculation of band structure is based on a self-consistent 6-band k·p formalism taking into account the valence band mixing, strain effect, and spontaneous and piezoelectric polarizations as well as(More)
Bovine horn is composed of a sheath of keratin overlying a bony core. Previous studies of the bovine horn sheath have focused mainly on its morphology and compositions. In the present paper, we performed a series of uniaxial tension, three-point bending, and fracture tests to investigate the structural and mechanical properties of the horn sheaths from(More)
The epitaxy optimization studies of high-quality n-type AlInN alloys with different indium contents grown on two types of substrates by metalorganic vapor phase epitaxy (MOVPE) were carried out. The effect of growth pressure and V/III molar ratio on growth rate, indium content, and surface morphology of these MOVPE-grown AlInN thin films were examined. The(More)
Strain-compensated InGaN quantum wells with tensile AlGaN barriers are analyzed as improved gain media for laser diodes emitting at 420-500 nm. The optical gain analysis, taking into account spontaneous and piezoelectric polarizations, exhibits significant improvement in the peak optical gain and differential gain for the strain compensated structures.
Depending on a biofilm lifestyle, Streptococcus mutans (S. mutans) is thought to be one of the primary causative agents of dental caries. Biofilm formation and adhesion are crucial physiological functions and virulence factors for S. mutans. Thus, attempts to control the development of dental caries only by inhibiting one of the several virulence factors(More)
Recombinant Streptococcus mutans glucan-binding protein D (rGbpD) was incorporated into poly(lactic-co-glycolic acid) (PLGA) microspheres which then were surface-coated with chitosan. The microspheres, with a mean diameter of ca. 1.8 µm, were intranasally administered in rats. There were elevated salivary immunoglobulin A and serum immunoglobulin G antibody(More)
Optimization of internal quantum efficiency (IQE) for InGaN quantum wells (QWs) light-emitting diodes (LEDs) is investigated. Staggered InGaN QWs with large electron-hole wavefunction overlap and improved radiative recombination rate are investigated for nitride LEDs application. The effect of interface abruptness in staggered InGaN QWs on radiative(More)