Measurement method of in-depth profiles of recombination lifetime in epitaxial Si layer with test element pattern

为实现高质量的硅光电探测器，研究了采用低阻衬底的高阻外延片。在界面处引入黄油层，对外延层的晶体质量有很大的影响。利用电导率调制技术自动测量脱毛层的复合寿命。在脱毛层表面形成横向p^+-n^—n^+二极管测试结构，以评估少数载流子寿命。复合寿命的深度分布由基板与顶表面之间的横向p^+-n^—n^+二极管和垂直n^+-n^—n^+结构的电流-电压曲线得到。我们测量了带缓冲层和不带缓冲层的脱毛器的寿命。此外，还测量了有缓冲层和没有缓冲层的光电二极管的光响应。复合寿命的分布取决于脱毛层的厚度，而不取决于缓冲层的厚度。通过测量复合寿命深度分布，证实了复合寿命在界面区变得非常均匀和长。然后在上述高质量外延片上制备了硅光电二极管，并对其外延片及其光电特性进行了评价。在热氧化过程中氧原子从衬底进入涂层的观察。脱膜中的氧是从底物中扩散出来的。

For the high quality Si Photodetector, the high resistivity epitaxial wafer using the low resistivity substrate were studied. The butter layer was introduced in the interface, and it was very effective on the crystal quality of the epitaxial layer (epilayer). Recombination lifetime of a epilayer is automatically measured by using the conductivity modulation technique. A lateral p^+-n^--n^+ diode test structure on the surface of the epilayer is formed to evaluate the minority carrier lifetime. Depth profiles of the recombination lifetime are obtained from current-voltage curves of a lateral p^+-n^--n^+ diode and a vertical n^+-n^--n^+ structure between the substrate and the top surface. We measure the lifetime in epilayers with and without a buffer-layer. In addition, photo-response of photodiodes with and without the buffer-layer is measured. Profiles of the recombination lifetime depend on the thickness of the epilayer but not on the thickness of the buffer-layer. Recombination lifetime in the epilayer became very uniform and long even in the interface region which was confirmed by measuring the lifetime depth profiles. Then Si Photodiode was fabricated on the above high quality epitaxial wafer and its epitaxial wafer and its optoelectric characteristics was evaluated. The observation of oxygen atoms from the substrate into the epilayer during thermal oxidation. The oxygen in the epilayer was diffused from the substrate.