Study On Optoelectronic Devices Based On 1D P-type Doped ZnO Nanomaterials

1D ZnO nano-structured materials, which have potential applications in emerging energy-related research field and optoelectronic research field, are fascinating because of their advantageous properties, including piezoelectricity, a wide direct bandgap, and a high exciton binding energy. The intrinsic n-type conduction characteristics of unintentionally doped ZnO nano-structured materials generally arise from the presence of native donor defects and hydrogen atoms. The compensating effects of the donor-type defects and the low solubility of p-type dopants are both responsible for the difficulty in fabricating 1D p-type ZnO nanomaterials. It is challenging to incorporate acceptor defects into ZnO nanomaterials by doping selected elements in order to obtain p-type conduction properties.In this paper, by incorporating selected elements (Cu, Ag, Sb) into ZnO, 1D p-type ZnO nanomaterials are grown on n-GaN film by chemical vapor deposition (CVD). These light emitting diodes (LEDs) which are based on 1D p-type ZnO nanomaterials/n-GaN films heterojunction emit different electroluminescence (EL) lights. Their EL mechanisms are also studied in this paper. Meanwhile, the UV photodetector based on sing p-ZnO:Sb/n-ZnO:Al homojunction core/shell nanowire is fabricated and studied. We find the device has self-powered ultraviolet photovoltaic performance. The main results are as following.1. A p-ZnO:Cu/n-GaN heterojunction LED is fabricated by growing cross-connected p-ZnO:Cu nanobushes on n-GaN film under oxygen-rich condition. This LED emits stable UV-free red EL light of 677 nm and 745 nm. The EL light of this LED is tuned from ultraviolet (UV) of ZnO/GaN to UV-free red though the electronic interfacial transition from the conduction band of n-GaN to the deep acceptor levels of p-ZnO:Cu. These deep levels help the EL red emission in the LED device.2. ZnO:Cu nanobushes which incorporate Cu element into ZnO are grown on p-GaN film by CVD. Incorporation of Cu atoms into ZnO can arouse Cu-related defect, which will influence EL light of LED based on ZnO:Cu/p-GaN heterojunction. The LED based on ZnO:Cu/p-GaN heterojunction emits blue-greenish EL light at p-GaN site at the positive bias voltage, and green EL peak gradually overtakes the blue EL peak with the increase of positive bias voltage. At reverse bias voltage, this LED not only exhibits yellow-green EL light at ZnO:Cu site, but also emits from orange to yellow EL light at p-GaN site with the increase of reverse bias voltage. The yellow-green EL light at ZnO:Cu site is composed of the green EL light resulting from substitutional Cu+ and Cu2+ at zinc site and yellow-orange light from ZnO:Cu/p-GaN interface.3. A p-ZnO:Ag/n-GaN heterojunction LED is fabricated by growing p-ZnO:Ag nanowire arrays on n-GaN film. This LED emits stable white EL light which is resulting from the intrinsic defects and impurity defects of p-ZnO:Ag. This p-ZnO:Ag/n-GaN heterojunction LED can provide some reference value for white LED cold light source.4. P-ZnO:Sb nanowire arrays by integrating Sb element into ZnO are grown on n-GaN film by CVD. P-ZnO:Sb/n-ZnO:Al core/shell nanowire arrays are obtained by directly depositing n-ZnO:Al film to muffle the top of p-ZnO:Sb nanowire via magnetron sputtering technology. The UV photodetector based on sing p-ZnO:Sb/n-ZnO:Al homojunction core/shell nanowire were fabricated by welding both ends of single p-ZnO:Sb/n-ZnO:Al homojunction core/shell nanowire with Pt onto the electrodes of submicron integrated circuit. This UV photodetector has the self-powered UV photoelectric response characteristics. The value of IUV/Ldurk at-1 V is 4.5, which indicates that this UV photodetector has good ultraviolet photodetection sensitivity characteristic.The research in this paper expands the application of 1D p-type ZnO nanomaterials in optoelectronic devices, which provides the reference for the fabrication of new-type LED cold light source and the self-powered UV photodetector.