Exciton relaxation in chalcogenide semiconductor investigated by time-resolved photoluminescence measurement

通过时间分辨光致发光测量研究硫族化物半导体中的激子弛豫

• 批准号: 07640445
• 负责人: MATSUDA Osamu
• 金额: $ 1.28万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640445/
• 关键词: Chalcogenide; Amorphous; Crystal; Photoluminescence; Electron-phonon interaction; Relaxation; Time-resolved measurement; Exciton

Amorphous chalcogenide semiconductors which contain the elements of group VI show various kinds of photo-induced structural changes such as photo-darkening, photo-bleaching, photo-crystallization, etc.. These changes are caused by lattice deformations which result from the relaxation of the photo-excited electrons through the strong electron-phonon interaction. It is also important that the amorphous states are not in the thermal equilibrium. The chalcogen atoms which are in two-fold coordinated are considered to play an important role, but the details of the mechanism is still not clear. For example, it is still unknown how the excited electron distorts the lattice.To know the relaxation process of the excited electron in the amorphous and crystalline GeSe_2 which is a typical chalcogenide semiconductor, the time resolved photo-luminescence measurement was carried out. Both phases have the band-gap in visible region (2.2-2.7eV). The excitation by band-gap light causes a broad Gaussian-shaped photo-luminescence in near-infra-red region (-1eV). The large Stokes-shift is due to the strong electron-phonon interaction. The continuous wave laser light is modulated by an acousto-optic modulator and then used for the excitation source of the time-resolved measurement. The measured time region was 100ns-3ms after the cut-off of the excitation light. There are many similarities in the spectral shape between the amorphous and crystalline GeSe_2. This result shows that the initial states of the luminescence are similar in both materials. As for the time-profile, the crystalline GeSe_2 shows the single exponential decay, while the amorphous GeSe_2 shows the extended exponential decay. The later is caused by the energy distribution of the luminescent centers by structural fluctuation in the glass.

非晶态硫族化合物半导体材料具有光致暗化、光致漂白、光致晶化等多种光致结构变化。这些变化是由晶格变形引起的，晶格变形是由光激发电子通过强的电子-声子相互作用而弛豫引起的。同样重要的是，非晶态不处于热平衡。双配位的硫族元素原子被认为起着重要的作用，但具体的机理尚不清楚。为了了解GeSe_2（一种典型的硫族半导体）中激发电子的弛豫过程，我们进行了时间分辨光致发光测量。两个相都具有可见光区的带隙（2.2-2.7eV）。在带隙光的激发下，在近红外区（~ 1 eV）产生了宽的高斯型光致发光。大的斯托克斯位移是由于强的电子-声子相互作用。连续波激光经声光调制器调制后作为时间分辨测量的激励源。测量的时间范围为激发光截止后100 ns-3 ms。非晶态GeSe_2和晶态GeSe_2的光谱形状有许多相似之处。该结果表明，两种材料的发光的初始状态相似。在时间曲线上，晶态GeSe_2表现出单指数衰减，而非晶态GeSe_2表现出扩展指数衰减。后者是由玻璃中结构涨落引起的发光中心的能量分布引起的。

项目成果

M. Nakamura: "Laser spot size dependence of photo-induced crystallization process in amorphous GeSe_2" Journal of Non-crystalline Solids. 198-200. 740-743 (1996)

M. Nakamura：“非晶 GeSe_2 中光诱导结晶过程的激光光斑尺寸依赖性”非晶固体杂志。

Y.Wang: "Temperahrie dependence of Raman spectra in amorphous,crystalline,and liguid GeSe_2" Proc.16th Inf.Conf.on Amorphors Semicond,Kobe,Japan,Sep4-8(1995). (in priwting).

Y.Wang：“非晶态、晶态和液态GeSe_2中拉曼光谱的Temperahrie依赖性”Proc.16th Inf.Conf.on Amorphors Semicond，神户，日本，Sep4-8(1995)。

O.Matsuda: "Photoemission and inverse-photoemission study on the electronic structure of p- and n-type amorphous Ge-Se-Bi films" Journal of Non-crystalline Solids. vol.198-200. 688-691 (1996)

O.Matsuda：“p 型和 n 型非晶 Ge-Se-Bi 薄膜电子结构的光电发射和逆光电发射研究”非晶固体杂志。

Y.Wang: "Structure and glass transition in Ge_xSe_<1-x> Studied by Raman scattering" Proc.23rd International Conference on the Physics of Semiconductors. 153-156 (1996)

Y.Wang：“通过拉曼散射研究Ge_xSe_<1-x>中的结构和玻璃化转变”Proc.23rd国际半导体物理会议。

Y.Wang: "Temperature dependence of Raman spectra in amorphous, crystalline, and liquid GeSe_2" Journal of Non-crystalline Solids. vol.198-200. 753-757 (1996)

Y.Wang：“非晶态、晶态和液态 GeSe_2 中拉曼光谱的温度依赖性”非晶态固体杂志。