Photoconductivity of self-assembled ZnO nanoparticles synthesized by organometallic chemistry

Abstract

We report on the photoconductivity properties of devices based on ZnO nanoparticles for UV detection. The nanoparticles were synthesized by organometallic chemistry, self-assembled on Si substrates covered by inter-digited metallic electrodes and annealed at 200 • C. The photoconductivity of these devices was measured for wavelengths ranging from 300 to 600 nm. The sensitivity of our samples at 350 nm excitation wavelength is about 1 A cm 2 W −1 , or 1200 A W −1 , with a visible rejection of 150. The photoconductivity strongly depends on pressure and is one order of magnitude larger under vacuum than at atmospheric pressure. Transient photoconductivity characteristics at atmospheric pressure and under vacuum are fitted using stretched exponential functions and quantitatively analysed. These results show the potential use of chemically prepared ZnO nanoparticles for UV and/or gas detection.

Optical Properties for Ti Doped Thin Zno Films Prepared By PLD

“…(3).This figure reveals that the increasing of Ti concentrations from 0 to 10 wt% leads to decrease the energy gap from approximately 3.3 to 2.2 eV respectively. This can be attributed to increase the mineral content and this result is in agreement with that observed by Carrey et al [2].Also this decrease in E g value after doping with Ti is attributed to that Ti introduces interband energy levels in the band gap of thin ZnO films which were responsible for the shift of optical E g to lower band gap energy or higher wavelength (red shift).…”

Photoluminescence and photoconductive characteristics of hydrothermally synthesized ZnO nanoparticles

“…3). UV peak may be attributed to ZnO band gap energy transition [40]. At ener− gies, lower than the band gap, the photosensitivity of ZnO NPs may be attributed to electronic transitions between deep levels and conduction band which is evidenced by PL spectra (Fig.…”

A high-resolution optically addressed spatial light modulator based on ZnO nanoparticles

“…Undoped ZnO is normally n-type because of oxygen vacancies in the material. [19][20][21] Oxygen atoms on the surface of a ZnO NP adsorb free electrons through a process of O 2 (g)1e 2 RO 2 2 , resulting in a depletion region of low dark conductivity near its surface. When the ZnO NP film is subjected to suitable UV light radiation, electron-hole pairs are generated.…”

“…This leads to an increase in the free electron density and a decrease in the thickness of the depletion region and hence increases the conductivity of the ZnO NP film. 20,[22][23][24] When the UV radiation is turned off, the oxygen atoms re-adsorb the free electrons again, decreasing the conductivity of the photoconductor film. The large surface-to-volume ratio of the ZnO NPs results in a large depletion region being formed on the NP surfaces in the dark state.…”