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 (LP MOCVD). In this complex structure

the ZnSeTe/ZnTe quantum well is a type Ⅱ 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. Pump probe experiment was done to study the exciton decay in CdZnTe well of the complex structure. Single exponential fitting of the pump probe result yields a down time 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.