以分子束磊晶法成長高摻雜氯的硒化鋅薄膜及其特性分析

摘要　　我們以分子束磊晶法在砷化鎵基板上成長了摻雜氯的硒化鋅薄膜，並進行光激發螢光的量測與分析。在不同載子濃度的硒化鋅薄膜的光激螢光光譜圖發現，隨著載子濃度的增加，摻雜氯的硒化鋅薄膜的能隙螢光強度會持續增強並伴隨藍位移，直到載子濃度超過8.8×1018 cm-3。我們認為這是由於電子能帶填滿效應持續增強所導致的結果。而載子濃度達1.6×1020 cm-3的樣品所發出的光激螢光總強度為最強，且晶體轉動曲線的半高寬為最小，這可能是因為摻雜了大量的氯原子取代硒原子，因而使晶格常數縮小，導致基板與磊晶層之間的晶格不匹配程度減少。此外，我們對有無摻雜氯的硒化鋅薄膜分別做了兩個小時的雷射照光與加熱至150 ℃的劣化測試實驗，結果發現兩者皆會使未摻雜的硒化鋅薄膜之螢光強度衰減，然而這兩個實驗對於載子濃度：1.6×1020 cm-3的樣品卻呈現兩極化的結果，我們認為這是由於雷射照光相較於加熱對樣品產生了較多的非輻射中心導致；同時，我們發現摻雜氯的硒化鋅薄膜相較於未摻雜的樣品，螢光強度衰減的行為大幅減緩。之後，我們在c平面的藍寶石基板上成長摻雜氯的硒化鋅薄膜，在光激螢光的量測中觀察到一個峰值位置在610 nm、半高寬116 nm的寬頻譜螢光。

關鍵字

分子束磊晶；硒化鋅；摻雜氯；劣化實驗

並列摘要

Abstract The characteristics of Cl-doped ZnSe films grown by molecular beam epitaxy on GaAs substrate have been investigated. The room-temperature PL intensity enhancement and energy peak blue-shift in the carrier concentration dependence PL results are attributed to band filling effect. The smallest FWHM in x-ray rocking curve were observed for the highest doping concentration sample. We think that this perhaps was due to the huge amount of Cl atoms substituted as the Se atoms and resulting in reducing the lattice-mismatch between epitaxial layer and substrate. Moreover, we do the two experiments for un-doped and Cl-doped ZnSe – exposing to laser light two hours and annealing to 150 ℃ two hours, respectively, for material degrade test. We found that the PL intensity of all samples were decrease after exposing to laser light two hours. But the PL intensity was increase after annealing to 150 ℃ two hours for the sample with carrier concentration 1.6×1020 cm-3.We think that the much more non-radiative center to be generated in the laser experiment than annealing experiment, so the PL intensity was always decrease in the laser experiment. Moreover, we have grown the Cl-doped ZnSe films on the c-plane sapphire substrate. A strong PL emission at wavelength of 610 nm with a very broad full with at half maximum (FWHM) of 116 nm was obtained at room-temperature.