The N–In codoped p-type ZnO films have been prepared by ultrasonic spray pyrolysis. X-ray photoelectron spectroscopy analysis confirmed the presence of nitrogen and indium in the codoped films, and the incorporation of indium causes the change in the chemical state of nitrogen, which promotes the formation of p-type conduction. Low resistivity of 1.7×10-2Ωcm, high carrier concentration of 2.44×1018cm-3 and Hall mobility of 155 cm2V-1s-1 at room temperature for the codoped films were obtained. A conversion from p-type conduction to n type in a range of temperature has been identified by the measurement of Seebeck and Hall effect.

The two-layer-structured ZnO p-n homojunctions were prepared on single-crystal Si (100) substrate by depositing undoped n-type ZnO film on N–In codoped p-type ZnO film using ultrasonic spray pyrolysis. The crystal structure and morphology of the obtained ZnO homojunctions were examined by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The two-layer structure was confirmed by secondary ion mass spectroscopy depth profile analysis. The current–voltage (I –V) characteristics derived from the undoped ZnO/N–In codoped ZnO two-layer structure clearly show the rectifying characteristics of typical p-n junctions.

Nitrogen-doped p-type ZnO (ZnO: N) films have been achieved by ultrasonic spray pyrolysis at atmosphere. The high structural quality of the obtained films was confirmed by x-ray diffraction, scanning electron microscopy, and photoluminescence spectra. Hall-effect and Seebeck-effect measurements indicate that the obtained p-type ZnO film shows a low resistivity of 3.02×10−2Ωcm, high carrier concentration of 8.59×1018cm−3, high mobility of 24.1 cm2/V s, and high Seebeck coefficient of 408.2 μV/K at room temperature. Furthermore, the two-layer structured ZnO p–n homojunctions were prepared by depositing n-type ZnO layer on p-type ZnO: N layer. The current–voltage curve derived from the two-layer structure clearly shows the typical rectifying characteristic of p–n junctions.

Undoped and N–In codoped ZnO films were deposited on Si(100) by ultrasonic spray pyrolysis. The structural, electrical and optical properties of the ZnO based films were investigated. Results indicate that the low-resistivity p-type ZnO film with the resistivity of 5.04×10−3 Ωcm, high mobility of 33.5 cm2/Vs, carrier concentration of 3.69×1019cm−3, and Seebeck coefficient of 825μV/K was obtained by the codoping of N and In. In the photoluminescence measurement, a strong near-band-edge emission was observed for both undoped and codoped films, while the deep-level emission was almost undetectable.

The heterojunction light-emitting diode with n-Zn0.8Mg0.2O/ZnO/p-Zn0.8Mg0.2O structure was grown on single-crystal GaAs(100) substrate by a simple process of ultrasonic spray pyrolysis. The p-type Zn0.8Mg0.2O layer was obtained by N–In codoping. A distinct visible electroluminescence with a dominant emission peak centered at ~450 nm was observed at room temperature from the heterojunction structure under forward bias conditions. The origin of electroluminescence emission was supposed to be attributed to a radiative recombination through deep-level defects in the ZnO active layer. The result reported here provides convincing evidence that ZnO based light-emitting devices can be realized at extremely low cost.