InAs/GaAs系列量子点研究

为了获得波长长、均匀性好和发光效率高的量子点,采用分子束外延(MBE)技术和S-K应变自组装模式,在GaAs(100)衬底上研究生长了三种InAs量子点。采用MBE配备的RHEED确定了工艺参数:As压维持在1.33×10-5Pa;InAs量子点和In0.2Ga0.8As的生长温度为500℃;565℃生长50nmGaAs覆盖层。生长了垂直耦合量子点(InAs1.8ML/GaAs5nm/InAs1.8ML)、阱内量子点(In0.2Ga0.8As5nm/InAs2.4ML/In0.2Ga0.8As5nm)和柱状岛量子点(InAs分别生长1.9、1.7、1.5ML,停顿20s后,生长间隔层GaAs2nm)。测得对应的室温光致发光(PL)谱峰值波长分别为1.038、1.201、1.087μm,半峰宽为119.6、128.0、72.2nm、相对发光强度为0.034、0.153、0.29。根据PL谱的峰位、半峰宽和相对发光强与量子点波长、均匀性和发光效率的对应关系,可知量子点波长有不同程度的增加、均匀性越来越好、发光效率显著增强。

Study of InAs/GaAs Quantum Dots

In order to get better property quantum dots(QDs) with longer wavelength,better uniformity and higher luminous efficiency,three types of InAs/GaAs QDs were researched and fabricated on GaAs(100)substrates by molecular beam epitaxy(MBE)technology through the S-K strained self-assembled mode.The process parameters were established by MBE with RHEED,in which As pressure is 1.33×10-5 Pa,the growth temperature of InAs QDs and In0.2-Ga0.8As is 500 ℃,the growth thickness of GaAs cover layer is 50 nm at 565 ℃.The vertical coupled QD(InAs 1.8 ML/GaAs 5 nm/InAs 1.8 ML),dot-in-well QD(In0.2Ga0.8As 5 nm/InAs2.4ML/In0.2Ga0.8As 5 nm) and columnar island QD(InAs,1.9,1.7,1.5 ML,respectively,then 2 nm interval layer GaAs after 20 s pause)were fabricated.The mesurement results show that the peak wavelengths of photoluminescence(PL)spectrum are 1.038,1.201 and 1.087 μm at room temperature,the full widths at half maximum(FWHM)of spectral peak are 119.6,128.0 and 72.2 nm,and the peak intensities are 0.034,0.153 and 0.29,respectively.According to the corresponding relationships of the peak wavelength of PL spectrum vs wavelength of QD,FWHM vs uniformity and peak intensity vs radiation efficiency,it indicates that the wavelengths of QDs increase differently,the uniformity is getting better and better,and the luminous efficiency can be enhanced evidently.