光斑尺寸对GaAs_(1-x)Bi_x光致发光谱线型的影响  

Effects of spot size on photoluminescence lineshape of GaAs_(1-x)Bi_x

作　　者：闫冰 陈熙仁[2] 刘锋[1] 邵军[2] YAN Bing;CHEN Xi-Ren;LIU Feng;SHAO Jun(Department of Physics,Shanghai Normal University,Shanghai 200234,China;State Key Laboratory of Infrared Physics,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China)

机构地区：[1]上海师范大学数理学院,上海200234 [2]中国科学院上海技术物理研究所红外物理国家重点实验室,上海200083

出　　处：《红外与毫米波学报》2019年第2期210-214,共5页Journal of Infrared and Millimeter Waves

基　　金：国家重点基础研究发展计划(2014CB643901);国家自然科学基金(61675224;61334004和U1531109);上海市基础研究重点项目(16ZR1441400;16JC1402400和17142200100);中国科学院上海技术物理研究所创新项目(CX-195;CX-151)~~

摘　　要：针对低激发功率密度光致发光(photoluminescence,PL)谱信噪比(signal-to-noise ratio,SNR)对GaAs_(1-x)Bi_x带尾能级探究的限制问题,基于傅里叶变换红外PL光谱实验系统对两个GaAs_(1-x)Bi_x外延膜开展变激发光斑尺寸PL光谱测试分析.结果表明,激发功率恒定时光斑直径增大导致PL峰位红移和线宽先降低后增大.这一现象是由于等效激发功率密度的降低而导致的.在保持激发功率密度为5. 1 W/mm2时,光斑增大不影响光谱线型但显著提升SNR.由此,低激发功率密度PL光谱的弱信号探测能力得以提高,有助光谱定量拟合分析.本工作表明,适当增大激发光斑尺寸有助于低激发功率密度PL光谱的SNR和弱信号分辨能力的提升.Lowexcitation-power density photoluminescence(PL)spectra suffered from poor spectral signal-to-noise ratio(SNR)and hence restricted the study of the band-tail states in GaAs1-xBix.We conduct laser spot-size-dependent PL measurements on two GaAs1-xBix epitaxial films by Fourier transform infrared spectrometer-based PL system with enhanced sensitivity.It is observed that(i)with constant excitation power,increase of laser-spot diameter leads to a redshift of the PL-peak position and a linewidth evolution of first decreasing and then increasing,which is attributed to the decrease of the equivalent excitation power density,and(ii)with a constant excitation power density of 5.1 W/mm2,the PL lineshape is unchanged while the SNR is significantly improved as the laser spot diameter rises.As a result,the weak transition features are well resolved in the PL spectra taken at lowexcitation pow-er density,and can be safely treated by spectral fitting analysis.The result indicates that adequate increase of excitation spot-size contributes to the improvement of the SNR and sensitivity as well for PL measurement at lowexcitation-power density.

关 键 词：光斑尺寸 信噪比 光致发光 GaAsBi 

分 类 号：O433.4[机械工程—光学工程]