- 學位論文
以化學浴沉積法製備未摻雜Cu2O薄膜之回火效應特性分析
Study on the annealing effects of undoped cuprous oxide films prepared by chemical bath deposition
摘要
氧化亞銅(Cu2O)具有直接遷移型能隙，能隙大約為2.1eV，在可見光區吸收係數大，穿透率低等特性，應用在太陽能電池研製上，將可增大太陽能電池對於入射太陽光的吸收波長範圍。 本實驗使用化學浴沉積法(Chemical Bath Deposition；CBD), 於兩種表面形貌不同的銅基板上進行未摻雜之n型氧化亞銅(undoped Cu2O)薄膜製備研究，並且比較不同回火方式分別為合金爐(RC2400)及紅外線回火(IR-Rurnace)。藉由熱探針法(Hot probe)、光激發螢光頻譜儀(Photoluminescence,；PL)、X-光繞射儀(X-ray diffraction；XRD)、掃瞄式電子顯微鏡(Scanning Electron Microscopy；SEM)、Alpha-step、電流電壓量測系統(Current-Voltage measurement；I-V)去分析薄膜特性。對於不同基板所製備之未摻雜氧化亞銅薄膜，其發光特性主要為1.72eV為二價氧空缺發光，經由高溫回火後出現2.03eV為激子發光(free exciton)，而電容電壓量測(C-V)分析出未摻雜氧化亞銅其載子濃度約為8ⅹ〖10〗^16 〖cm〗^(-3) - 2ⅹ〖10〗^17 〖cm〗^(-3)，利用電容頻率(C-f)與電導頻率(G-f)量測分析並計算出其介面狀態密度(Interface state density distribution；Nss )約3.6378×〖10〗^5 〖cm〗^(-2) 〖eV〗^(-1)-3.08423×〖10〗^8 〖cm〗^(-2) 〖eV〗^(-1)，以SEM分析薄膜表面型態可得知成長於不同表面形貌之基板及不同回火方式，其薄膜之表面型態也不同。
並列摘要
Cuprous oxide is a direct band-gap semiconductor, energy gap size is 2.1eV with a high absorption coefficient in the visible region. Undoped cuprous oxide (Cu2O) thin films are fabricated on two different surface morphology copper (Cu) substrates by chemical bath deposition (CBD) method. The polycrystalline Cu2O films are annealing by two different tempering systems in nitrogen (N2) at different temperatures, one is alloying furnace (RC2400) and another is IR-Furnace. The Cu2O films are characterized by hot probe measurement, PL, XRD, SEM, Alpha-step and I-V measurement. The optical properties of undoped Cu2O films were investigated by low temperature PL measurement. The obvious peak of undoped Cu2O is 1.72eV. The band at 1.72eV is produced by the recombination of excitons bond to a double charge oxygen vacancies . Using capacitance-voltage measurement to analysis the carriers concentration of n-type undoped Cu2O films and the carriers concentration derived is about 8ⅹ〖10〗^16 to 2ⅹ〖10〗^17 〖cm〗^(-3). Besides, using capacitance versus frequency curves and conductance versus frequency curves to calculate the interface state density distribution of undoped Cu2O. The interface state density distribution with a value of 3.08423×〖10〗^8 〖cm〗^(-2) 〖eV〗^(-1) from (E_c-0.0048) to 3.6378×〖10〗^5 〖cm〗^(-2) 〖eV〗^(-1) from (E_c-0.2698). From the SEM analysis, we can find out that the surface morphology is not the same by using two different substrates and tempering systems.