作　　者： ; ; ;

机构地区： 厦门大学物理与机电工程学院物理学系

出　　处： 《发光学报》 2005年第1期77-82,共6页

摘　　要： 通过对GaP1-xNx混晶的瞬态发光特性的研究,揭示了在低组分下N杂质从NNi对束缚激子的特性逐渐向高组分下形成GaP1-xNx混晶的杂质带的演变。在较低组分下,样品的发光由NNi对束缚激子及其声子伴线构成,从NN1 到NN4 的衰减时间分别在 90~30ns变化。当组分提高到x^1. 3%以上时,样品的发光呈现出一个宽带,并按单指数规律衰减,辐射复合寿命大约在数十个纳秒量级,且随着N组分的增加,寿命相对减小;但在最高组分(x^3. 1% )时,其寿命仍与NN4 束缚激子的寿命相当 ( ~30ns),说明GaP1-xNx混晶新形成的杂质带仍然保持束缚激子较长的辐射复合寿命。且该杂质带低能端载流子的寿命比高能端载流子的寿命长,导致了其时间分辨谱向低能端的移动。同时在低组分样品的时间分辨谱的测量中,直接观察到了从较浅NN对束缚激子向较深NN对束缚激子的能量传输现象。 GaP_(1-x)N_x alloys (or heavily doped nitrogen in GaP) are usually referred as abnormal alloy due to their giant band gap effect. Recently many attentions have been paid to the study on their photoelectric properties. In this paper, the radiative decay and time-resolved spectra were employed to investigate the transient photoluminescence of GaP_(1-x)N_x alloys with x=0.05%～3.1% at low temperature. For the low N concentration (x=0.05%～0.81%) samples with emission of different NN_i lines and their sidebands, the (lifetime) is about 30～100 ns in accord with the decay time of NN_4, NN_3 and NN_1 center. For the samples with N concentration up to 1.3%～3.1%, the photoluminescence shows a broaden band and their radiative recombination exhibit the typical exponential decay with 56～36 ns, much longer than that of the free excitons (usually about several nanoseconds), but shorter than that of the samples of GaP_(1-x)N_x with x=0.43%～0.81%, whose photoluminescence composed mostly of NN_4 and its sidebands. And it has a trend that, compared to the NN_i bound excitons, the radiative decay time of the alloys decrease with increasing the N composition. However the lifetime only decrease to the same level of that of the NN_4 center (about 30 ns) which indicates that the newly nitrogen impurity band of GaP_(1-x)N_x alloy with x～3% has kept the indirect property of bound excitons with long lifetime, although many PL properties suggested that it has direct band gap. At the same time, due to the longer lifetime for the carriers at the lower energy, the decay time at different detected energies showed that, the higher the detected energy, the shorter the lifetime. In addition to the luminescence decay, the time-resolved photoluminescence were detected. For the high nitrogen concentration samples (GaPN alloys), the energy peak shifts to the lower energy side with the time delay due to the shorter lifetime at higher energy side. For the low nitrogen concentration samples, especially for x=(0.05%) and 0.12%, the relative

关 键 词： 混晶 时间分辨谱 能量传输

领　　域： [理学] [理学]