Selective Area Growth and Characterization of GaN Nanorods Fabricated by Adjusting the Hydrogen Flow Rate and Growth Temperature with Metal Organic Chemical Vapor Deposition

CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.

Growth and Characterization of InAs1-xSbx with Different Sb Compositions on GaAs Substrates

InAs1-xSbx with different compositions is grown by molecular beam epitaxy on （100）-oriented semi-insulating GaAs substrates. The increase of Sb content in the epilayer results in the deterioration of crystal quality and surface morphology. Hall measurements show that the carrier concentration increases with the composition of Sb. The electron mobility decreases initially, when Sb composition exceeds a certain value, and the mobility increases slightly. In this work, we emphasize the comparison of crystal quality, surface morphology and electrical properties of epilayers with different Sb compositions.

Growth and Characterization of InSb Thin Films on GaAs(001) without Any Buffer Layers by MBE

We report the growth of InSb layers directly on GaAs （001） substrates without any buffer layers by molecular beam epitaxy （MBE）. Influences of growth temperature and V/Ⅲ flux ratios on the crystal quality, the surface morphology and the electrical properties of InSb thin films are investigated. The InSb samples with room- temperature mobility of 44600cm2/Vs are grown under optimized growth conditions. The effect of defects in InSb epitaxial on the electrical properties is researched, and we infer that the formation of In vacancy （VIn） and Sb anti-site （SbIn） defects is the main reason for concentrations changing with growth temperature and Sb2/In flux ratios. The mobility of the InSb sample as a function of temperature ranging from 90 K to 360K is demonstrated and the dislocation scattering mechanism and phonon scattering mechanism are discussed.

Growth and characterization of InAs quantum dots with low-density and long emission wavelength

The growth parameters affecting the deposition of self-assembled InAs quantum dots （QDs） on GaAs substrate by low-pressure metal-organic chemical vapor deposition （MOCVD） are reported. The low-density InAs QDs （- 5 × 10^8cm^-2） are achieved using high growth temperature and low InAs coverage. Photoluminescence （PL） measurements show the good optical quality of low-density QDs. At room temperature, the ground state peak wavelength of PL spectrum and full-width at half-maximum （FWHM） are 1361 nm and 23 meV （35 nm）, respectively, which are obtained as the GaAs capping layer grown using triethylgallium （TEG） and tertiallybutylarsine （TBA）. The PL spectra exhibit three emission peaks at 1361, 1280, and 1204 nm, which correspond to the ground state, the first excited state, and the second excited state of the ODs, respectively.

Purification and characterization of growth stimulating diadenosine triphosphate from porcine myocardial tissue

The proliferationof vascular smooth muscle cells (VSMC) plays a role in the maintenance of hypertension and atherosclerosis. Diadenosine polyphosphates have been identified as modulators of the cardiovascular system. We detected the existence of diadenosine polyphosphates in the heart and studied their growth stimulating effect on VSMC. Porcine cardiac tissue was deproteinated with perchloric acid and concentrated with a preparative reversed phase C18 column. Then the extract was separated with a size exclusion column, an anion exchange column, and an affinity column. It was then chromatographed with an anion exchange HPLC and a reversed phase HPLC and a purified substance was obtained. Med. Klinik I, Nephrol. Labor, Univ. Klinik Marien hospital, University of Bochum, Herne, Germany (Luo JK, Wang H, Schlüter H, JankowskifJ, Potthoff W, Tepel M and Zidek W) Using the BrdU method, this substance was shown to have a growth stimulating effect that is dose-dependent on VSMC. Matrix assisted laser desorption/ionization mass spectrometry (MALDI MS) analysis showed that the molecular mass of the substance was 757.0, the same as diadenosine triphosphate (AP 3A). UV spectrum indicated the maximum absorption at 259 nm, similar to that of adenosine. Postsource decay (PSD) MALDI MS showed that the substance contained adenine, adenosine, AMP, ADP, and ATP, respectively. Enzymatic cleavage revealed that phosphates in this molecule connected adenosine in 5' position. It was determined from the above data that the substance was Ap 3A. In this study the existence of Ap 3A was demonstrated in the heart. It has a growth stimulating effect on VSMC.