摘要
为了研究低维半导体结构中的激子过程,并进一步实现超快速的激子衰减,设计了一种新型的(CdZnTe,ZnSeTe)/ZnTe复合量子阱结构,并用低压金属有机化学气相沉积方法(LPMOCVD)制备出来。用泵浦 探测方法,采用反射式光路测量了该复合结构中CdZnTe/ZnTe量子阱的激子衰减,单指数衰减拟合给出690fs的下降沿时间。
As a key pole of an optical computer, optical switches interest many people recently. However, it is difficult to improve the turndown rate of optical switch because of the limit of lifetime of carriers (or excitons). In order to accelerate the decay of excitons, a new type of (CdZnTe,ZnSeTe)/ZnTe complex quantum wells were designed and fabricated via low pressure metal organic chemical vapor deposition method (LPMOCVD). In this complex structure, the ZnSeTe/ZnTe quantum well is a typeⅡ quantum well. Compared with the adjacent CdZnTe/ZnTe quantum well, the ZnSeTe/ZnTe quantum well has lower n=1 electron level and wider energy gap. So it can accept the carriers tunneled from the CdZnTe/ZnTe quantum well with not affecting the optical nonlinear property of the CdZnTe/ZnTe quantum well. The substrate was GaAs [100]. The widths of layers in CdZnTe/ZnTe/ZnSeTe were 3nm/8nm/9nm, respectively. It was expected that the excitons formed in the CdZnTe/ZnTe well would tunnel into the ZnSeTe/ZnTe well before the recombination. By means of shortening the lifetime of excitons in the CdZnTe well, faster turndown speed will be obtained. Photoluminescence and absorption spectra were employed to characterize the complex quantum wells. Pumpprobe experiment was done to study the exciton decay in CdZnTe well of the complex structure. Singleexponentialfitting of the pumpprobe result yields a downtime of 691±79fs, which is shorter than the exciton life time of single CdZnTe quantum wells in some publications. It can be considered that there exists efficient tunneling from CdZnTe well to ZnSeTe well.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2003年第3期257-260,共4页
Chinese Journal of Luminescence
基金
国家攀登计划
国家自然科学重大基金(69896260)
国家自然科学基金(60077015)
中科院百人计划
中科院创新工程资助项目
