Investigation On Properties Of Sb Doped SnO₂Thin Films And Homojunction Device Prepared By CVD Method

SnO2is a wide-band-gap semiconductor with bandwidth of3.6eV at room temperature,which is applied widely in many fields, such as gas sensors, transparent electrodes andoptoelectronic devices and so on due to its high optical transparency, low resistivity, andhigher chemical and physical stability. But SnO2is intrinsically n-type materials, therefore,most efforts have been focused attention to obtain p-type SnO2materials. In this paper, wehave synthesized different concentration Sb doped SnO2thin films and p-SnO2:Sb/n-SnO2homojunction by simple chemical vapor deposition method. The major research achievementsare listed below:(1) SnO2thin films with different Sb concentration were grown on Al2O3substrates bychemical vapor deposition method. The results showed that the morphologies of SnO2thinfilms become more smoothly, the size of the crystal grains larger and the crystal quality hasimproved with increasing Sb concentration. This indicated that small amounts of Sb whichincorporated into SnO2have functions as a surfactant. In addition, we also found that withincreasing Sb concentration, the optical band gap of the sample appeared blue shift. Moreover,the Hall measurements results indicated that the Sb doped SnO2thin films was p-typeconductivity, and the optimal Sb2O3/SnO mass ratio for sample is approximately1:5.(2) The Sb-doped SnO2films and p-SnO2:Sb/n-SnO2homojunction device wassynthesized on Si and Al2O3substrates by simple CVD method. The investigated results ofX-ray diffraction (XRD), scanning electron microscope (SEM) and Hall measurementindicated that SnO2thin films grown on Al2O3has highly crystal quality, and the film surfaceis smooth and dense. Hall measurements results indicated that the sample grown on Al2O3was p-type conductivity. I–V characteristics show that the p-n homojunction devices whichprepared on both Si and Al2O3substrates have good rectifier characteristics, the forward turnon voltage is2.5V and3.8V, respectively. These results also illustrate that the most suitablesubstrate to SnO2material is sapphire.