In_(0.2)Ga_(0.8)As/GaAs单量子阱PL谱温度特性及其机制

测量了不同阱宽In0.2Ga0.8As/GaAs单量子阱的PL谱的峰值波长和荧光谱线半峰全宽随温度的变化。利用Varshni公式对实验峰值波长进行拟合,得到了新的参数。结果表明,无位错应变量子阱带隙仍具有其体材料的特性:荧光谱线半峰全宽随温度升高迅速展宽,这主要归因于声子关联作用增强和激子热离化为自由载流子所致;阱宽越窄荧光峰值能量越高,将其与量子尺寸效应的理论计算结果进行了比较。文中还考察了谱线半峰全宽和阱宽的关系,利用合金无序对这一现象进行了解释。

Temperature Dependence of the Photoluminescence Properties and the Research on the Mechanism of In0.2Ga0.8As/GaAs Single Quantum Well

The technique of photoluminescence(PL) spectra is an important method for studying the properties of semiconductors and quantum wells since its high sensitiveness, convenience and non-destructive. This technique was used to study the single quantum well(QW) of In0.2Ga0.8As/GaAs in this paper.Different PL spectra were reported under different temperature,which ranged from 125 K to 260 K for a certain sample, and the PL spectra of the samples with different quantum well width were also reported.The paper reported that, for a certain sample, the peak of its PL spectra moved towards long wavelengh ranges with the temperature increa-sing,which means that the band gap of the SQW becomes narrower. Detail consideration suggested that this property was able to be described by the equation of Varshni for the bulk materials. So, the SQW is similar to its bulk material at this point. This was mainly because within certain thickness of SQW, there was no lattice misfit dislocation, and the fundamental structure of the energy gap will not change. It was also reported that, at certain temperature,the narrower was the SQW, the wider was its band gap. We performed a brief calculation by solve Schrdinger equation,and found that the experimental result fitted to the theoretical calculation.The relationship between full width at half maximum (FWHM) of PL peak and temperature of a certain sample and the relationship between (FWHM) and SQW width of different samples were also reported, at the same time, theoretical explanation was presented for these phenomenon.