In+Cd共掺杂ZnO薄膜的光电性能研究

Optical and electrical properties of In+Cd co-doped ZnO thin films prepared by PLD method

通过脉冲激光沉积(PLD)在石英玻璃基底上沉积了四元Zn0.86Cd0.11In0.03O(ZCIO)合金半导体薄膜。其中,Cd的掺杂是用以改变ZnO的光学禁带宽度,In是用以提高载流子浓度。X射线衍射(XRD)分析证实,ZCIO具有六方纤锌矿结构而没有其它相(如CdO和In2O3相)出现。场发射扫描电子显微镜(FE-SEM)观察到ZCIO薄膜的晶粒尺寸要比未掺杂ZnO的小。所有薄膜在可见光范围内都有很高的透过率(≈85%)。最重要的是,在保持了Zn1-xCdxO薄膜的光学特性外,ZCIO薄膜的电学性能得到了改善,低的电阻率(4.42×10-3Ω·cm)和高的载流子浓度(5.50×1019cm-3),使得它比Zn1-xCdxO薄膜更具应用价值。

Zn0.86Cd0.11In0.03O（ZCIO） alloy semiconductor thin film was deposited on quartz substrate by pulsed laser deposition （PLD） technique at room temperature. Cd is used to change the optical band gap and In is used to increase the carrier concentration of the ZnO thin film. The X-ray diffraction （XRD） studies confirm that the structure of Zn0.86Cd0.11In0.03O is hexagonal wurtzite without CdO phase, keeping the crystalline structure and lattice parameters close to those of ZnO film. The cold field emission scanning electron microscope shows that the grain size of Zn0.86Cd0.11In0.03O film is smaller than that of ZnO. XPS measurement is used to prove that In has been doped into ZnO thin films. These thin films are highly transparent （-85%） in visible region of solar spectrum. The PL spectra and the hand gap of the Zn0.86Cd0.11In0.03O film show substantial red shift to the visible light region, which can be interpreted in terms of band gap modulation due to Cd doping. Most importantly, the electrical properties of Zn0.86Cd0.11In0.03O thin film are highly improved with In doping. It has low resistivity （4. 42 ×10-3Ω·cm） and high carrier concentration （5.50 ×10^19cm-3）. Both the low electric resistivity and large transparent wavelength range enable this film a promising candidate for window layer in solar cells and other possible optoelectronic applications.