Low Temperature Epitaxial Growth of Rare Earth Doped Silicon and SiliconGermanium Alloys

摘要

PL and EL from a forward biased PN junction have been observed from Er doped Siproduced in this investigation. The material was deposited epitaxially in a low temperature process (500 deg C) involving PECYD using an ECR source. The dopant source was a metal organic compound, tris (bis trimethyl silyl amido) Er (III), which contained three nitrogen atoms bonded directly to Er. This bonding arrangement was beneficial in forming an intact, optically active center in the epitaxial Si material. The metal organic dopant precursor used however contained 18 C atom which to a large extent also became incorporated in the deposited film. Attempts to operate the fabricated PN junctions in reverse bias breakdown failed due to excessive leakage in the material caused by the high level of carbon impurities. Later work shifted to growing the epitaxial layer doped with only Er, with no co-dopants to improve the electrical transport properties of the material. This would also answer some basic physical questions about the role of co-dopants in the emission properties of the Er center. This was accomplished by adding an Er sputter gun to the reactor, and operating it during the PECVD growth of Si. We are still in the process of getting some of the bugs out of this process but we see no physical reason why it should not yield significant reverse bias EL.