Guotong Du

Preparation of intrinsic and N-doped p-type ZnO thin films by metalorganic vapor phase epitaxy

The intrinsic p-type ZnO thin films were prepared by controlling the oxygen partial pressure during growth. The E2 (high) mode at 432.2cm−1 appeared in the Raman spectrum of the film. The photoluminescence spectra taken at 77 K showed the emission band C in the violet region, which originated from zinc vacancy and varied in intensity in accordance with the quantity of the carrier concentration in the films. The N-doped p-type ZnO films were realized by N2 plasma. The Raman spectrum showed the dominant A1 (LO) mode at 580cm−1, that was the result of the host-lattice defects generated by N dopant rather than the N-related local vibration modes.

Visual-infrared electroluminescence emission from ZnO∕GaAs heterojunctions grown by metal-organic chemical vapor deposition

The light-emitting diode of p-ZnO∕n-GaAs heterojunction was grown by metal-organic chemical vapor deposition. The p-ZnO films have been formed by the doping As atoms which diffuse into ZnO film from GaAs substrate. The p-type behavior of As-doped ZnO films based on As-doped p-ZnO∕n-GaAs, p-ZnO∕p-GaAs heterojunction was studied by carrying out I-V measurements and x-ray photoelectron spectroscopy. The I-V characteristic of p-ZnO∕n-GaAs heterojunction showed characteristic of rectifying diode and visual-infrared electroluminescence emission under forward current injection at room temperature. The I-V of the heterounction had a threshold voltage of ∼2.5V.

1.1μm near-infrared electrophosphorescence from organic light-emitting diodes based on copper phthalocyanine

We demonstrated near-infrared organic light-emitting devices employing copper phthalocyanine (CuPc) doped into 4,4′-N,N′-dicarbazole-biphenyl (CBP). Room-temperature electrophos-phorescence was observed at about 1.1μm due to transitions from the first excited triplet state to the singlet ground state (T1-S0) of CuPc. There existed very weak emission of CBP from undoped devices, and at lower doping concentrations (⩽12wt%) the driving voltages of doped devices were higher than that of undoped devices. The results indicated that Forster [Ann. Physik. (Leipzig) 2, 55 (1948)] and Dexter [J. Chem. Phys. 21, 836 (1953)] energy transfers play a minor role in these devices, and direct charge trapping appears to be the dominant mechanism.

Cu related doublets green band emission in ZnO:Cu thin films

Cu-doped ZnO (ZnO:Cu) thin films were grown on Si (111) substrate by low-pressure metal-organic chemical vapor deposition equipment. The crystal structures and optical properties of as-grown sample were examined. X-ray diffraction patterns indicated a lattice relaxation after the Cu doping. The incorporation of Cu atoms into ZnO film and its existence in a bivalent state were demonstrated by x-ray photoelectron spectroscopy measurements. Low-temperature photoluminescence was carried out at temperature of 11.4 K for both unintentionally doped and Cu-doped ZnO films. A characteristic green-luminescence with fine structure consisted of doublets emission peak was observed, which was believed to be associated with Cu doping. A theoretical model based on hydrogen analog has been proposed to explain this phenomenon. It provides new information about the detailed role of Cu in ZnO thin films.

Hexagonal phase-pure wide band gap ε-Ga2O3 films grown on 6H-SiC substrates by metal organic chemical vapor deposition

In this paper, hexagonal structure phase-pure wide-band gap e-Ga2O3 films were grown by metal organic chemical vapor deposition on 6H-SiC substrates. The e-Ga2O3 films with good crystal quality were verified by high-resolution X-ray diffraction. The out-of-plane epitaxial relationship between e-Ga2O3 films and 6H-SiC substrates is confirmed to be e-Ga2O3 (0001)//6H-SiC (0001), and the in-plane epitaxial relationship is also confirmed to be e-Ga2O3 ⟨ 112¯0⟩//6H-SiC ⟨ 112¯0⟩. The SEM and AFM images show that the e-Ga2O3 films are uniform and flat. The e-Ga2O3 films are thermally stable up to approximately 800u2009°C and begin to transform into β-phase Ga2O3 at 850u2009°C. Then, they are completely converted to β-Ga2O3 films under 900u2009°C. The high-quality e-Ga2O3 films with hexagonal structure have potential application in the optoelectronic field.

Room temperature electroluminescence from arsenic doped p-type ZnO nanowires/n-ZnO thin film homojunction light-emitting diode

AbstractnThe highly arrayed arsenic doped p-ZnO nanowires/n-ZnO thin film homojunction light-emitting diode was fabricated on semi-insulated Si substrate. The homojunction was consisted of high-quality n-ZnO thin film grown by metal–organic chemical vapor deposition technology following arsenic doped ZnO nanowires grown by chemical vapor deposition. The device shows good rectification characteristic with a turn-on voltage of ~4.8xa0V and reverse breakdown voltage of ~18xa0V. Moreover, two distinct electroluminescence bands centered at 2.35 and 3.18xa0eV are detected from this device under forward bias at room temperature.

The lattice distortion of β-Ga2O3 film grown on c-plane sapphire

The β-Ga2O3 film is grown on c-plane sapphire (Al2O3) substrate using metal organic chemical deposition method. According to high resolution X-ray diffraction measurement results, the epitaxial relationship between β-Ga2O3 film and c-plane sapphire was confirmed. The β-Ga2O3 film is (

Unintentionally doped high resistivity GaN layers with an InGaN interlayer grown by MOCVD

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