13:30 〜 15:30
▲ [20p-PB2-7] Optimization of ZnO Nanowire Films for npn/pnp Bipolar Transistors
キーワード：p-type ZnO, ZnO nanowires, nanowire thin films
Zinc oxide is considered as a promising material for semiconductor device applications. Nevertheless, due to native donor defects in ZnO, p-type ZnO has remained a controversial material. Antimony doped p-type ZnO NWs with a stability of over 18 months was demonstrated through hydrothermal growth method. It is also possible to encourage lateral growth in ZnO nanowires to produce ZnO films by adding sodium citrate to the solution. However, the transverse conductivity of these nanowire films was poor due to the high concentration of interfacial defects. Annealing is possible means of decreasing these defects and improve the film quality. In this study, a variety of annealing parameters are investigated to increase the crystal quality of grown ZnO films.
ZnO seed layer was deposited on Si substrate before nanowire film growth. To produce the films, we made a solution of of zinc nitrate, hexamethylenetetramine (HMTA), and sodium citrate. An Sb glycolate dopant was added to the growth solution at a concentration of 1% relative to zinc. Then ammonium hydroxide was added to the solution to inhibit self-nucleation and precipitation in solution. The solution was heated up and the substrate was placed floating face down on the surface. To prepare the multilayer films, the substrate was put into a fresh solution for continued growth after growing the first layer. The fabricated samples were annealed at 450 ℃ for 10 min.
Scanning electron microscope images taken from cross section of the sample are shown in Fig 2. These results prove that annealing process was successfully improved the morphology of ZnO nanowire film and n/p ZnO films were formed successfully on Si substrates. The next step for this work is to apply this annealing technique to double and triple layer structures to produce functional ZnO electronics.
ZnO seed layer was deposited on Si substrate before nanowire film growth. To produce the films, we made a solution of of zinc nitrate, hexamethylenetetramine (HMTA), and sodium citrate. An Sb glycolate dopant was added to the growth solution at a concentration of 1% relative to zinc. Then ammonium hydroxide was added to the solution to inhibit self-nucleation and precipitation in solution. The solution was heated up and the substrate was placed floating face down on the surface. To prepare the multilayer films, the substrate was put into a fresh solution for continued growth after growing the first layer. The fabricated samples were annealed at 450 ℃ for 10 min.
Scanning electron microscope images taken from cross section of the sample are shown in Fig 2. These results prove that annealing process was successfully improved the morphology of ZnO nanowire film and n/p ZnO films were formed successfully on Si substrates. The next step for this work is to apply this annealing technique to double and triple layer structures to produce functional ZnO electronics.