MOCVD-Ga_xIn_(1-x)As_yP_(1-y)/InPDBR结构的晶格振动

Lattice Vibrations of MOCVD-Ga_xIn_(1-x)As_yP_(1-y)/InP DBRs Structures

利用微区Raman散射技术研究了MOCVD-GaxIn1-xAsyP1-y/InPDBRs结构的晶格振动。在InP衬底上生长的与InP晶格匹配的四元合金Ga0.4In0.6As0.85P0.15中包含三种主要的振动模式,分别归属于类InAs、类GaAs和类GaInP。随着Ga0.4In0.6As0.85P0.15与InP交替生长构成的DBRs结构周期数增加,Raman散射谱中三种振动模式的谱线线型发生明显变化,类InAs振动强度不变,谱线窄化,峰值位置向低频方向移动,类GaAs和类GaInP振动强度逐渐减弱。同时类InAs与类GaAs振动强度比增大。Raman散射研究中声子的限制效应表明多层结构生长过程中界面存在非完整晶态。

The lattice vibrations of the MOCVD-GaxIn1-xAsyP1-y epilayers and MOCVD-GaxIn1-xAsyP1-y/InP Distributed Bragg reflectors（DBRs） are investigated by micro-Raman scattering techniques. The used DBRs samples were formed with Ga0.4In0.6As0.85P0.15/InP alternative layers grown on the S-doped high quality （ 100 ） InP substrates in an atmospheric or low pressure metal organic chemical vapor deposition （MOCVD） system made up in our laboratory. The lattice constant and composition parameters （x, y） were determined using double crystal X-ray diffraction, scanning electronic microscope-photoelectron spectra and photoluminescence （PL） measurements. Raman spectra were measured at room temperature using the 488 nm line of Ar ion laser as an exciting source. The Raman signal was collected in the near back-scattering configuration and analyzed with a monochromator. The Raman spectra exhibit three major modes of vibrations in the Ga0.4In0.6As0.s5P0.15 grown on the lnP substrates. They are attributed to InAs-like, GaAs-like respectively. The Raman spectra line-shape of the three major modes of vibrations clearly c quaternary alloy and GaInP-like, hanged with the increasing of period number of DBR. The intensity of the InAs-like vibration is not changed, but its full width at half-maximum（FWHM） narrowed, the peak value location moved in the direction of the low-frequency. The intensity of the GaAs-like and GaInP-like gradually weaken. Ratio of intensities of InAs- and GaAs-like vibrations increased with the increasing of period number of DBR. The quaternary alloy Ga04In0.6As0. 85P0.15 was in the region of immiscibility. It was found that the surfaces of the samples grown in the region of immisicibility are rough. The interface quality between the Ga0.4 In0.6 As0.85 P0.15 and InP was effected. The restrictive effect of the phonon in the Raman scattering investigations showed that the non-integrity crystalloid appeared during the growth of the multi-layer structure.