多孔矽與多孔矽/鍺合金的發光研究

Abstract

在本文之中,由於SiGe的材料特性與Si不同,所以我們用其作為多孔結構發 光機制的研究,且可藉著不同結構,厚度及 Ge含量的多孔SiGe薄膜,而發現 許多不同的發光特性,其中SiGe薄膜是藉著ultrahigh vacuum/chemical vapor deposition (UHV/CVD)設備成長於P型矽晶片上,並使用電化學陽極 反應來進行蝕刻,由以上的實驗結果,我們認為多孔結構發光原因應該是量 子效應與Si-H鍵在多孔結構表面的passivation效果所造成的,最後由PL光 譜與EL照片中可看出其發光波長不大相同,我們認為這可能是由於發光區 域的不同所造成的 The luminescence properties of porous Si and porous SiGe was studied in this thesis. The SiGe alloy and related heterostructures have been a subject of intensive research recently because of the possibility of fabracting high speed devices. The porous SiGe and SiGe/Si heterostructures, however, were never throughly studied before. In this thesis, various porous Si and SiGe alloy layers with different thickness and compositions were investigated. The luminescence behavior was correlated with the layer parameters. It was found that the PL line width decreases as the porous layer become thicker indicating quantum behavior. The emission peak shifts toward long wavelength in SiGe samples as Ge composition increases. In SiGe/Si heterostructures, the intensity of the luminescence from SiGe increase dramatically as a result of carrier confinement provided by the heterostructure. The aging behaviors of porous Si and porous SiGe were also studied. We found that the luminescence intensity of SiGe has a much faster degradation rate than Si. From FTIR measurement, we found that the Si-H bonds are much weaker in SiGe than in Si. The breakdown of the Si-H bonds causes the degradation of luminescence in porous SiGe.