Tomographic detection of micro-defects in semi-conductions due to light scattering and photoluminescence imaging

由于普通半导体晶体中的缺陷密度相当低，因此确定监视体积对于获得关于晶体中缺陷的正确信息是非常重要的。这里的体积被定义为一个单一的监督试验搜索，并应等于或略大于缺陷的倒数density.The以下两个步骤的调查导致了成功的和新颖的使用一个普通的IR光散射层析成像（LST）仪器为此目的。(1)由于载流子从激光束照射的位置扩散出发射光致发光（PL），因此用于LST的由激光束光学注入的载流子引起的光致发光（PL）的监视厚度通常远大于用于LST的激光束直径。因此，PL映射是非常有效的搜索晶体中的低密度缺陷，因为这些缺陷通常作为PL杀手中心，有时，复合中心。(2)通过使用精细聚焦的激光束进行逐层层析成像，仔细地测量PL映射中的强度调制位置。通过上述两种方法的互补结合，可以清楚地观察到缺陷。

Since the defect density in ordinary semiconductor crystals is fairly low, determination of the surveillance volume is very important to get correct information about defects in the crystals. Here the volume is defined as that to be searched by a single surveillance trial and should be equal to or a little larger than the reciprocal density of the defects.The following two-step investigation resulted in successful and novel use of an ordinary IR light scattering tomography (LST) instrument for this purpose. (1) The surveillance thickness of photoluminescence (PL) due to carriers optically injected by a laser beam for LST is usually much larger than that of the laser beam diameter for LST, because the carriers diffuse out emitting PL from the position illuminated by the beam. Thus PL mapping is very effective to search for low density defects in the crystals since the defects act as usually PL killer centers and, sometimes, recombination centers. (2) The intensity modulated positions in the PL mapping were carefully surveyed by layer-by-layer tomography using a finely focused laser beam.By complimentary combination of the above two methods the defects will be clearly observed.