Study On Irradiation Effects Of Quantum Well Material Caused By Free Electron Laser

The studies on free electron laser (FEL) and quantum well materials (QWM) are both the front domain of high-tech in nowadays. However, the studies on irradiation effects of QWM by FEL are limited, and the problem is very novel. In this paper, it introduces what are PEL and QWM at first. And then it discusses the basic theories of FEL acting on QWM. At last, it studies the experiment phenomena of the QWM with FEL irradiation. We used FEL with wavelength of 8.92 m and peak power density of 1.84 105W/cm2 to irradiate the QWM for half an hour, and measured the photoluminescence(PL)spectrums of QWM irradiated. It is found that the QWM was annealed by FEL. And the FEL with the same wavelength and peak power density of 2.64 105W/cm2 will bring damages to QWM and even make the QWM appear quantum wells intermixing. These phenomena show that FEL will make the temperature of QWM increase, and the stress result from uneven temperature will destroy the integrity of lattices. We also used FEL with wavelength of 8.92 m and electric-field strength of 25kV/cm to irradiate the QWM and measured the Hall effect simultaneously at different temperatures. It is found that FEL made the mobility increase and the electron concentration reduce. These phenomena show that FEL can change the density of states for electrons, make the electrons in ground subband excite to higher subband and change the electron concentration by varying the depletion length.