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Non-Essentiality of alr and murI Genes in Mycobacteria

Amino acids are the building blocks of life. If DNA is the blueprint, amino acids are the lumber that proteins are built with. Proteins are built with left-handed, L- forms of amino acids. Bacteria have an essential cell wall component that happens to be an exception: peptidoglycan. Bacteria have enzymes called racemases that convert L- amino acid ...

In situ accurate control of 2D-3D transition parameters for growth of low-density InAs/GaAs self-assembled quantum dots

A practical route towards fabricating GaN nanowire arrays

GaN nanowire (NW) arrays have been fabricated by the electrodeless photoelectrochemical (PEC) etching method for the first time. Under appropriate conditions, the etching process is just a dislocation-hunted process, in which the etching solution "digs down'' along the threading dislocations, resulting in the formation of GaN NWs by preferentially ...

High-reflectivity AlN/GaN distributed Bragg reflectors grown on sapphire substrates by MOCVD

Numerical study of strained InGaAs quantum well lasers emitting at 2.33 mu m using the eight-band model

We investigate the band structure of a compressively strained In(Ga)As/In(0.53)Ga(0.47)As quantum well (QW) on an InP substrate using the eight-band k.p theory. Aiming at the emission wavelength around 2.33 mu m, we discuss the influences of temperature, strain and well width on the band structure and on the emission wavelength of the QW. The wavel...

Study of metamorphic InGaAs/GaAs quantum well laser materials grown on GaAs substrate by molecular beam epitaxy

The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy(MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic structure precisely. The threading dislocations are reduced. We also optimize the growth and annealing parameters of the InGaAs quantum...

Effect of high temperature AlGaN buffer thickness on GaN Epilayer grown on Si(111) substrates

Crack-free GaN epitaxial layer was obtained through inserting 80 nm graded AlGaN buffer layer between GaN epilayer and high temperature AlN buffer on 2-in Si(111) substrates by metal organic chemical vapor deposition. This paper investigated the influence of AlGaN buffer thickness on the structural properties of the GaN epilayer. It was confirmed f...

Surface characterization of AlGaN grown on Si (111) substrates

Up to 500 nm thick crack-free Al(0.25)Ga(0.75)N and Al(0.32)Ga(0.68)N epilayers have been grown on Si (111) substrates. The surface morphology of samples was investigated by an optical microscope and a scanning electron microscope (SEM). Pits and shale-like surface structure have been observed. XRD rocking curve measurements indicate the crystal qu...

Molecular beam epitaxy growth of GaAs on an offcut Ge substrate

Influence of growth temperatures on the quality of InGaAs/GaAs quantum well structure grown on Ge substrate by molecular...

Molecular beam epitaxy growth of an InxGa1-xAs/GaAs quantum well(QW) structure(x equals to0.17 or0.3) on offcut(100) Ge substrate has been investigated. The samples were characterized by atomic force microscopy, photoluminescence(PL), and high resolution transmission electron microscopy. High temperature annealing of the Ge substrate is necessary t...