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Evaluation of Multilayer Structure by Using new High Sensitivity PAS

使用新型高灵敏度 PAS 评估多层结构

基本信息

批准号：
01460074
负责人：
HATA Tomonobu
金额：
$ 4.1万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

We developed a PAS (Photoacoustic Spectroscopy) using a transparent transducer. It is possible to evaluate an absorption coefficient of semiconductors quantitatively and to perform a reproducible experiment. As the light can irradiate through a transparent transducer, a generated acoustic slignal is directly detected by this transducer. Consequently, the sensitivity is considerably improved and there are no sample geometry limitations. Especially, this method is effective to evaluate the surface layer of the samples, ion implanted layers, interface of heteroepitaxial layers, and so on.1. It is so sensitive that it is possible to detect the signals from the ion implanted layer. As this layer is so thin (900-3200, *) that this method is also applicable to evaluate the surface damages of semiconductors.2. At low energy region we could detect a weak absorption which is generated by the localized states of ion implanted layer. By estimating this value, it is possible to evaluate the recovery process of the thin ion implanted layer by thermal annealing, quantitatively.Next, PA signals from GaInP/GaAs heterostructure and multilayer structures of semiconductors were observed and the following results were obtained.3. Each absorption edge of multilayer structure is determined separately by the PA dips and large phase shift.4. Nonradiative defects are detected clearly at GaInP/GaAs interface.5. The PA dip occurs at interfacial layer when the signal origin moves from one to another layer as irradiated wavelength changes. This is because the transducer detects two different phase signals with different amplitudes of each layer at the same time.6. Now we are trying to separate the signals from piezoelectric and piroelectric effects and to make it possible to evaluate the optical and thermal constants quantitatively by comparing with the theoretical analysis.

我们开发了一种使用透明换能器的光声光谱技术。可以定量地评估半导体的吸收系数并执行可重复性的实验。由于光可以通过透明换能器照射，因此产生的声光信号直接由该换能器检测。因此，灵敏度大大提高，并且没有样本几何限制。特别是，该方法对样品的表面层、离子注入层、异质外延层的界面等的评价是有效的。它是如此敏感，以至于有可能检测到来自离子注入层的信号。由于这一层很薄(900-3200，*)，因此该方法也适用于评估半导体的表面损伤。在低能区，我们可以检测到离子注入层的局域态产生的微弱吸收。通过对该值的估计，可以定量地评价热退火薄离子注入层的恢复过程。其次，观察了GaInP/GaAs异质结和半导体多层结构的PA信号，得到了以下结果。多层膜结构的每个吸收边分别由PA的跃迁和较大的相移决定。在GaInP/GaAs界面处有明显的非辐射缺陷。当信号的起始点随着辐照波长的变化从一层移到另一层时，在界面层出现PA凹陷。这是因为换能器同时检测到每层不同幅度的两个不同的相位信号。现在，我们正试图将信号从压电效应和热电效应中分离出来，并通过与理论分析的比较来定量地估计光学常数和热常数。