Disorder Characterization of Oxide/Silicon Interfaces from I-V Curves
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Disorder Characterization of Oxide/Silicon Interfaces from I-V Curves Louis Nemzer, Fredy R. Zypman1 Gerofsky Physics Center, Yeshiva University, 2495 Amsterdam Ave., New York, NY, USA ABSTRACT In this paper, we present results on transmission-energy curves through quantum wells with disordered interfaces. We propose a rule to process experimental data to obtain information about the degree of disorder. INTRODUCTION The goal of this paper is to clarify the effect of defects on the performance of quantum multi-layered devices. More concretely, this study finds the dependence of current-vs-voltage (I-V) curves on interface roughness. In the last two years a new type of quantum well and superlattice was designed based on silicon and oxygen [1]. These semiconductor-atom structures (SAS) are built by alternating layers of silicon and thin films of oxygen, thus creating quantum structures similar to the traditional superlattices. These SAS have good electroluminescence and photoluminescence in the optical spectrum and may therefore form the basis of future all-Si integrated circuits with both electrons and photons. Transmission Electron Microscopy images [2] show that the SAS have stacking fault and dislocations in substantial quantities as to affect measurable quantum quantities [3], such as response time and transmission. Substantial experimental work has been done [2] to try to understand why in SAS, silicon may grow epitaxially after the oxygen barrier, which is never the case in Si/SiO2 interfaces. During growth, it the oxygen valve is left open, then a large number of defects is generated in bulk silicon. However, by controlling the oxygen rate supply, it is possible to produce silicon on both sides of the oxygen interface with defect densities below 109/cm2. Nevertheless, the oxygen layer itself is typically broken up in islands in such a way as to provide for continuation of the epitaxy of silicon, by means of lateral growth, but more experimental work is needed to uncover the precise structure. What is clear is that it is technically possible to produce SAS with negligible bulk defects but that still present strain and disorder at the oxygen interface. In particular, the shape and size of the island cannot be controlled. In order to contribute to the understanding of the Si-O interfaces, we study the effect that interface disorder has on the I-V curves of electron transport through
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SAS. We expected that the quality factor (Q-factor, the ratio between peak height and peak width) of the I-V curves at resonance in the presence of defects be degraded as compared with I-V curves for crystalline structures. This hypothesis turned out to be correct so we also characterized the loss quantitatively. A large variety of Optoelectronics materials are commonly made of layers of Silicon-based or Gallium Arsenide-based materials. Typical methods of fabrication are Chemical Vapor Deposition (CVD) or Molecular Beam Epitaxial (MBE). In either case, the degree of control of layer thickness and surface coverage is
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