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Li S.,South China Normal University | Li S.,Key Laboratory of Electroluminescent Devices | Su J.,South China Normal University | Su J.,Key Laboratory of Electroluminescent Devices | And 7 more authors.
Journal of Crystal Growth | Year: 2010

We have investigated the growth of magnesium-doped GaP (GaP:Mg) layers on GaN by metalorganic chemical vapor deposition. The hole carrier concentration increased linearly from 0.8×1018 to 4.2×1018 cm-3 as the Bis(cyclopentadienyl) magnesium (Cp2Mg) mole flow rate increased from 1.2×10-7 to 3.6×10-7 mol/min. However, the hole carrier concentration decreased when the CP 2Mg mole flow rate was further increased. The double crystal X-ray diffraction (DCXRD) rocking curves showed that the GaP:Mg layers were single crystalline at low CP2Mg molar flow. However, the GaP:Mg layers became polycrystalline if the CP2Mg molar flow was too high. The decrease in hole carrier concentration at high CP2Mg molar flow was due to crystal quality deterioration of the GaP layer, which also resulted in the low hole mobility of the GaP:Mg layer. © 2010 Elsevier B.V. All rights reserved.

Li S.-T.,South China Normal University | Li S.-T.,Key Laboratory of Electroluminescent Devices | Cao J.-X.,South China Normal University | Cao J.-X.,Key Laboratory of Electroluminescent Devices | And 6 more authors.
Chinese Physics B | Year: 2010

The growth of GaP layer on GaN with and without buffer layers by metal-organic chemical vapour deposition (MOCVD) has been studied. Results indicate that the GaP low temperature buffer layer can provide a high density of nucleation sites for high temperature (HT) GaP growth. These sites can promote the two-dimensional (2D) growth of HT GaP and reduce the surface roughness. A GaP single crystal layer grown at 680 °C is obtained using a 40-nm thick GaP buffer layer. The full-width at half-maximum (FWHM) of the (111) plane of GaP layer, measured by DCXRD, is 560 arcsec. The GaP layer grown on GaN without low temperature GaP buffer layer shows a rougher surface. However, the FWHM of the (111) plane is 408 arcsec, which is the indication of better crystal quality for the GaP layer grown on GaN without a low temperature buffer layer. Because it provides less nucleation sites grown at high growth temperature, the three-dimensional (3D) growth is prolonged. The crystalline quality of GaP is lightly improved when the surface of GaN substrate is pretreated by PH3, while it turned to be polycrystalline when the substrate is pretreated by TEGa. © 2010 Chinese Physical Society and IOP Publishing Ltd.

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