磷化镓中铋束缚激子的多声子辐射跃迁

在温度4.2K—110K范围内测量了GaP:Bi外延层的光致发光谱。发光谱中只出现Bi束缚激子辐射复合的谱线。由于Bi束缚激子的局域电子态与四周品格存在着相当强的耦合,晶格弛豫引起的多声子辐射复合非常明显,发射光谱呈现相当宽的橙色谱带,且声子伴线“丰富”并彼此重迭。实验结果表明:从4.2K—40K A类线与B类线并存,B类线强度随温度上升而减弱最终难于辨认,77K以上A类线支配着整个光谱。对复杂的发光光谱谱线进行了识别和分类,并借助于电子计算机用曲线拟合法对光谱进行精确分解,首次求出各系列的黄昆因子(Huang-Rhys factor)。较大数值的黄昆因子表明晶格弛豫是强的。

MULTIPHONON RADIATIVE TRANSITION OF EXCITONS BOUND TO Bi IN GaP

The behaviour of bismuth in GaP is interesting not only because of the possibility of highly efficient radiative recombination at low temperature,but also the "rich" fine structure of the luminescence spectrum,which has not yet been finally identified.An investigation on the luminescence spectra of GaP grown by epitaxy from Ga-Bi melts containing 10at% Bi has been made.Photoluminescence measurements were performed at temperatures between 4.2K-110K.The samples were excited by the 4880Åline from an argon-ion laser.The excitation power was 140mW.The spectra were taken by using an ASI-50D double grating monochromator with a R106 photo-multiplier.The output signal of the photomultiplier was amplified by a lock-in amplifier and recorded by X-Y recorder.