Chemical State Analysis of Heavily Phosphorus-doped Epitaxial Silicon Films Grown on a Si (100) Substrate with XPS

 Phosphorus-doped silicon (Si:P) has been actively researched because of its novel opto-electronic and mechanical properties which make it for potential applications in photo-voltaics and strain engineering. It is therefore... [ view full abstract ]

 Phosphorus-doped silicon (Si:P) has been actively researched because of its novel opto-electronic and mechanical properties which make it for potential applications in photo-voltaics and strain engineering. It is therefore important to study fundamental chemical analysis of Si:P to successfully introduce into future devices. Although some previous reports have addressed the chemical state analysis of Si:P film by X-ray photo-electron spectroscopy (XPS), the chemical states between phosphorus and silicon were not well characterized because of the low concentration and injection method of the dopant.

 In this study, we studied the chemical states of Si:P film grown on Si (100) substrate by reduced pressure chemical vapor deposition (RPCVD) with different phosphorus dopant concentration to analyze the bonding between phosphorus and silicon. High resolution X-ray photo-electron spectroscopy (HR-XPS) was performed using a monochromatic Al Kα X-ray source (hν = 1486.7 eV) with a pass energy of 40 eV. To investigate the chemical bonding, XPS spectra for the Si 2p and P 2p region were deconvoluted and the binding energies were calibrated with a Si 2p spectrum as a reference Si-Si bond, 99.4 eV. Secondary ion mass spectroscopy (SIMS) was carried out to confirm the phosphorus concentration.

 As shown in figure, the P 2p spectra were deconvoluted in to three well-resolved contributions. One is plasmon loss peak of Si 2p, another is P-Si 2p_1/2 (detected at 129.9 eV) and the other is P-Si 2p_3/2 (detected at 129.0 eV). The P-Si 2p_1/2 and 2p_3/2 peak intensities were found to increase with greater dopant concentrations. This chemical state analysis can be helpful in understanding the properties of Si:P films.