ochuan Xia

Study on the luminescence properties of n-ZnO/p-Si hetero-junction diode grown by MOCVD

n-ZnO/p-Si hetero-junction light emitting diodes were fabricated using a metal organic chemical vapour deposition (MOCVD) technique. Room temperature (RT) photoluminescence (PL) spectrum showed an intense main peak at 377 nm and a weak deep-level emission. The I–V characteristics of the n-ZnO/p-Si hetero-junction showed rectifying diode behaviour at different temperatures. At a low bias voltage, typical values of the ideality factors were determined to be 2.84 at 77 K and 1.94 at 300 K, indicating that the junction had good diode characteristics. RT electroluminescence (EL) was detected under forward bias, which covered a broad visible range (400–600 nm) corresponding to defect-related emission. The remarkable difference between the PL and EL spectra was ascribed to their different excitation and recombination processes. Infrared EL emission at Si band gap energy based on the n-ZnO/p-Si hetero-junction structure was also detected.

Study on the p-MgZnO/i-ZnO/n-MgZnO light-emitting diode fabricated by MOCVD

A p-MgZnO/i-ZnO/n-MgZnO light-emitting diode was fabricated on a GaAs substrate by metal–organic chemical vapour deposition. The I–V curve of the device exhibited typical rectifying behaviour of the p–i–n diode and the forward turn-on voltage was about 7 V. An obvious ultraviolet peak can be observed in the electroluminescence spectrum corresponding to the radiative recombination of carriers. The dependences of the characteristics on the thickness of the ZnO interlayer were also studied. The results showed that the intensity of the UV peak increased as the thickness of the ZnO layer decreased. A clear blue shift can also be observed at the same time. The thickness of the ZnO layer had an important effect on the optical qualities of the device.

Study on the properties of MgxZn1?xO-based homojunction light-emitting diodes fabricated by MOCVD

A MgxZn1−xO p–n homojunction light-emitting diode (LED) was fabricated on the GaAs substrate by metal–organic chemical vapour deposition (MOCVD). The I–V curve of the device exhibited typical rectifying behaviour of the p–n diode. The forward turn-on voltage was about 3.5 V. The photoluminescence spectra of the n-type and p-type MgxZn1−xO layers exhibited obvious near-band-edge emission peaks and weak deep-level emission peaks. In the electroluminescence (EL) spectra of the diode, a broad emission band from 2.3 to 2.8 eV can be observed. The emission band near 3.31 eV did not appear until the injection current reached 180 mA. The differences in the EL spectra between ZnO and MgxZn1−xO LEDs are also discussed.

Green electroluminescence from ZnO/n-InP heterostructure fabricated by metalorganic chemical vapour deposition

Vertically aligned ZnO films were deposited on n-InP by metalorganic chemical vapour deposition. X-ray diffraction, field emission scanning electron microscopy and photoluminescence measurements demonstrated that the ZnO films had good quality. By evaporating AuZn electrodes on both ZnO and InP surfaces, a ZnO-based light emitting device was fabricated. Under forward voltage, weak green emissions can be observed in darkness.

Effect of the magnesium composition on the properties of MgxZn1−xO-based homojunction light-emitting diodes

MgxZn1?xO p?n homojunction light-emitting diodes (LEDs) with different Mg compositions were fabricated on GaAs (1?0?0) substrates by metal?organic chemical vapor deposition. The effects of variation of the Mg composition on the properties of the LEDs were researched. The I?V curve exhibited typical rectifying behavior of a p?n diode. The near-band emission peaks in the photoluminescence and the deep-level emission peaks in the electroluminescence spectra were both blueshifted due to the wide band gap. The full-width at half-maximum value and the intensity of the DLE peak were also affected by the increasing defect density.

Optical and electronic properties of ZnO:P/n+-Si heterostructures fabricated by metalorganic chemical vapour deposition

ZnO:P/n+-Si heterostructures were fabricated on n+-Si substrates by metalorganic chemical vapour deposition. The substrates were heavily doped with phosphorus. The crystallinity and optical properties of ZnO films were characterized by photoluminescence spectra and x-ray diffraction, respectively. X-ray photoelectron spectroscopy (XPS) showed that phosphorus atoms existed in ZnO films. The current–voltage (I–V) curve showed current rectification characteristic behaviour.