CAJ | 학술논문

研究了在CdSe/ZnSe自组装量子点中CdSe量子点的发光随着激发光强度变化的特性.发现当激发强度(I)变化3个数量级的时候,量子点发光的峰位、峰形都没有发生明显的变化.通过公式L∝Ik(其中,是激发光强度,L是量子点发光强度,k是非线性系数)得到非线性系数k值.实验结果表明:在温度由21 K升高到300 K的过程中,k值随温度变化可以分为3个区域:当温度低于120 K时,k值接近于1;然后,随着温度升高,k值慢慢变小;最后,随温度进一步升高,k值由200 K时的0.946迅速减少到0.870.结合发光随温度变化的实验结果,确认在120 K以下发光主要来源于束缚激子复合.在温度由200 K升高到300 K的过程中,非线性系数的单调减小主要归因于随着温度的升高,发光部分来自于由自由电子或空穴到束缚态能级(FB)的复合.进一步通过分析量子点发光的积分强度随着温度的变化的实验结果,发现发光强度随温度升高而减弱的主要原因是材料中的缺陷或者位错等提供非辐射渠道.
연구료재CdSe/ZnSe자조장양자점중CdSe양자점적발광수착격발광강도변화적특성.발현당격발강도(I)변화3개수량급적시후,양자점발광적봉위、봉형도몰유발생명현적변화.통과공식L∝Ik(기중,시격발광강도,L시양자점발광강도,k시비선성계수)득도비선성계수k치.실험결과표명:재온도유21 K승고도300 K적과정중,k치수온도변화가이분위3개구역:당온도저우120 K시,k치접근우1;연후,수착온도승고,k치만만변소;최후,수온도진일보승고,k치유200 K시적0.946신속감소도0.870.결합발광수온도변화적실험결과,학인재120 K이하발광주요래원우속박격자복합.재온도유200 K승고도300 K적과정중,비선성계수적단조감소주요귀인우수착온도적승고,발광부분래자우유자유전자혹공혈도속박태능급(FB)적복합.진일보통과분석양자점발광적적분강도수착온도적변화적실험결과,발현발광강도수온도승고이감약적주요원인시재료중적결함혹자위착등제공비복사거도.
We have investigated the excitation-intensity-dependent optical properties of CdSe/ZnSe self-assembled quantum dots (QDs) at different temperature. When excitation intensity (I) is varied by three orders of magnitude,the photolumineseence (PL) morphology and peak positions appear to be independent on excitation intensity. The nonlinear coefficient k obtained by a relation of L ∝Ik in the temperature ranges of 21～300 K shows regularity which is described in three temperature regions:k is close to 1, when the temperature is below 120 K, it slightly decreases with increasing temperature in ranges of 120～200 K and it rapidly decreases from 0.946 to 0.870 with the temperature in the ranges of 200～300 K. Taking the temperature dependence of PL into account, we have confirmed that the bound excitonic recombination is a dominant recombination mechanism below 120 K. The nonlinear coefficient k monotonously decreases in the temperature ranges of 120～300 K, which is attributed to increasing transition from free-to-bound (FB) exciton with increasing temperature. Furthermore, the temperature dependence of integrated PL intensity reveals that defects and dislocations in the material provide nonradiative channels to quench the luminescence.