The absolute concentration of oxygen in polycrystalline InN was measured using a combination of Rutherford backscattering and x-ray photoemission spectroscopy. Polycrystalline InN was grown on quartz and glassy carbon at 500 °C by molecular-beam epitaxy using In metal and activated nitrogen species generated in rf plasma. The optical bandgap of polycrystalline InN increased from 1.55 to 2.27 eV with increasing oxygen concentration from 1% to 6%. Polycrystalline InN with an optical bandgap of 1.9 eV, which has often been reported, contains oxygen of a molar fraction of 3%.
There is a very narrow two-phase region in the CdS-CdTe pseudobinary system in high temperature, and we can obtain mixed crystals in almost the entire range of composition. Lattice parameters of CdSxTe1-x satisfy “Vegard's law”. Both of the solidus and the liquidus curves determined by D.T.A. have the same minimum temperature of 1071°C at x=0.2. At 1000°C the crystal structure is the cubic zincblende (x<0.2) and the hexagonal wurtzite (x>0.2). In the solid phase there is a miscibility gap, and it is attributed to lattice strain resulting from the large difference in atomic sizes of the VIth elements. On account of the strain energy contributions to the thermodynamic free energy the solidus curve is calculated from the experimental liquidus curve, and it agrees very well with the experimental data.
We describe a low-resistance quasi-ohmic contact to p-ZnSe which involves the injection of holes from heavily doped ZnTe into ZnSe via a Zn(Se,Te) pseudograded band gap region. The specific contact resistance is measured to be in the range of 2–8×10−3 Ω cm2. The graded heterostructure scheme is incorporated as an efficient injector of holes for laser diode and light emitting diode devices, demonstrating the usefulness of this new contact scheme at actual device current densities.
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