Zheng Zhuhong, Fan Xiwu. LUMINESCENCE OF FREE EXCITONS IN ZnTe CRYSTAL UNDER HIGH EXCITATION DENSITY[J]. Chinese Journal of Luminescence, 1989,10(2): 117-122
Zheng Zhuhong, Fan Xiwu. LUMINESCENCE OF FREE EXCITONS IN ZnTe CRYSTAL UNDER HIGH EXCITATION DENSITY[J]. Chinese Journal of Luminescence, 1989,10(2): 117-122DOI:
Luminescence of ZnTe crystal in the near band edge region has been investigated at 77K.Several explanations on the origin of near band edge emission have been reported. Cingolana et al
[3]
. considered the origin as band-gap shrinkage appeared under high excitation density
Jin et al
[9]
. considered it as bound-free transition
and Panowicz et al
[5]
. considered it as exciton-carrier scattering.In present work
crystals of undoped p-ZnTe were grown by Bridgman method and photoluminescence spectra were measured by Model 44W spectrometer with RCA-C31034 photomultiplier under excitation of 3371Å line of a N
2
laser at 77-300K.The photoluminescence spectra of the ZnTe crystal under different excitation density at 77K are shown in Fig. 1.The spectra under lower excitation density consist of three bands peaked at 5252Å(E)
5336Å(FB
0
)and 5394Å (FB
1
)respectively. With increasing excitation density the width of E band becomes large and its peak position shifts towards longer wavelength
but the peak positions of FB
0
and FB
1
bands do not change. The FB
0
and FB
1
bands correspond to free-to-bound transition and its replica associated with 1 LO phonon
respectively. The E band is caused by exciton-carrier interactions.