- 學位論文
寬能隙氧化物半導體薄膜之摻雜特性研究
Study on the doping properties of wide band-gap oxide semiconductor films
摘要
本實驗裡我們利用常壓式金屬有機化學氣相沉積(AP-MOCVD)製作摻雜銀之p型氧化鋅(ZnO)薄膜，我們以二乙基鋅及水分別做為Zn與O元素的材料來源，銀為p型摻雜源。本研究中在矽(100)基板上使用電子槍蒸鍍10nm銀後，成長氧化鋅底膜，藉由適當的回火溫度550℃使銀向上擴散至後續所成長的氧化鋅中，並讓銀原子取代鋅原子，達成p型摻雜。於此論文中我們針對未摻雜、未回火及回火的氧化鋅薄膜特性進行分析比較，首先X光繞射(XRD)分析光譜之主峰顯示六角纖鋅礦結構(wurtzite structure)，於(002)晶面有從優取向趨勢；霍爾量測電洞濃度可達1021 cm-3、遷移率2.47 cm2/Vs以及電阻率2.27×10-3Ωcm，此外由所製備的p型氧化鋅於低溫4.8K下所量測的光激螢光(PL)光譜中顯示出在3.03eV有明顯的來自自由電子與受體雜質所束縛的電洞之復合(FA)發光，進一步驗證了利用銀膜擴散摻雜技術成功地製備了p型ZnO薄膜。 氧化亞銅摻氯以化學浴沉積法成功製備並達成N型導電型態，本研究中利用純銅片作為基板，硫酸銅(CuSO4．5H2O)和氯化銅溶液分別做為銅和氯的摻雜源，成長溫度和成長時間控制在100℃及1小時，X光繞射(XRD)分析光譜之主峰顯示(111)面為結構主要面向，低溫4.8K下所量測的光激螢光(PL)光譜中顯示出兩個位置1.72V和1.88eV有明顯的發光，分別為氧空缺(VO2+)及氯所造成的雜質能接所造成的發光，此外文獻中提到1.34eV的銅空缺則因溶液有大量的Cu+離子所填補空缺而偵測無此發光，我們也改變了不同摻雜量進行分析研究。
並列摘要
Ag-doped ZnO (ZnO:Ag) thin film have been fabricated by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). Diethylizinc (DEZn) and water vapor were used as the precursors of Zn and O, respectively, and Ag was as p-type doping source. The p-type conduction was achieved through the following processes. First, a 10-nm-thick Ag film was evaporated on Si(100) substrate by electron beam evaporation. Then, an undoped ZnO thin film of 0.4 m thick was deposited on top, followed by an annealing performed at 550°C in O2 ambient for 40 min. The annealing process would enhance the thermal diffusion behavior of Ag atoms in ZnO lattice, produce enough quantities of AgZn and activate them to result in p-type conductivity of ZnO:Ag film. X-ray diffraction measurements show the dominance of (002) peak for the ZnO:Ag specimen with annealing treatment, demonstrating a polycrystalline film of wurtzite structure with a highly c-axis preferred orientation. Moreover, Hall effect measurements indicated the p-type conductivity of the ZnO:Ag film with the hole concentration of about 1021 cm-3 and mobility of 2.47 . Low temperature photoluminescence spectroscopy conducted at 4.8 K exhibited an emission line at 3.03 eV, typifying the free electron to acceptor (FA) recombination mechanism, and therefore the doping effect of Ag is recognized. Cl-doped Cu2O (Cu2O:Cl) thin film have been fabricated by chemical bath deposition (CBD). The samples in this study were grown on poly copper substrates by chemical bath deposition system. Copper sulfate (CuSO4．5H2O) and Cupric chloride (CuCl2) were used as the source Cu and doping source Cl, respectively. The polycrystalline copper plates (200um thick, 99.96% purity, 2cm × 2cm size ) were used as substrates. The beakers containing the solution were maintained at 100 °C for 1hr in order to obtain the proposed films. About the deposition solution, we controlled various quantities about CuSO4 and CuCl2. Besides, we defined 10M-2 as 1 unit. The solution containend CuSO4 dissolved in 500ml deionized water. The XRD results show that peak at (111) plane is the most prominent peak in the sample. The optical properties of Cu2O films were investigated by low temperature PL measurements. There are two obvious peaks about 1.72eV and 1.88eV on PL spectra. The band at 1.72 eV is produced by the recombination of excitons bound to a double charged oxygen vacancies (VO2+). Beside, the band at 1.34eV is produced by the recombination of bound excitons at copper vacancies (VCu), but in our study no VCu recombination emission, we think it cause by Cu+ rich and fill vacancy. we measure the Cu2O:Cl sample, there are obvious at 1.88eV produce, it may Cl- caused to dopant level emission. Besides, various quantities of CuCl2 being added the 1.88eV emission produce regularity.