气相外延ZnSe单晶膜室温蓝色发射的复合过程

随着激发密度的增加,ZnSe外延单晶膜的室温蓝带Es′(～4650Å)表现出红移和展宽,其行为与77K时得到的相一致。在200-300K温度范围内,测得Es′谱带的热激活能为19meV,它与ZnSe晶体自由激子的束缚能20meV十分接近。上述结果从实验上进一步证明了ZnSe外延单晶膜室温蓝带Es′起源于受导带中自由电子散射的自由激子的衰减。

THE RECOMBINATION PROCESS OF THE BLUE EMISSION AT ROOM TEMPERATURE FROM VPE ZnSe EPILAYER

Blue electroluminescence of ZnSe MIS diodes had been obtained in the near band edge emission region[1,2] and the stimulated emission had also been observed in this region[3,4]. Many work in the origin of the blue emission of ZnSe at room temperature (RT) had been reported. The blue emission of ZnSe at RT was contributed by free exciton emission[5], the overlapping between free exciton emission and band-to-band transition[6], the emission due to the excitons which bounded to neutral donors[7], the band-to-band radiative recombinations[8], the bound-to-free transitions[9], and the exciton-carrier interaction[10,1].In our earlier work, attention was focused on the identification of the free exciton emission[11] and the determination of the origin of the blue emission band[1] in ZnSe crystals. In this paper the recombination process of the blue emission at RT from VPE ZnSe epilayers was studied. It was found that the origin of the blue emission at RT could be contributed by the exciton-carrier interactions.