Boron contamination of i n s i t u heated silicon surfaces

Abstract

Interfacial p doping due to B contamination is routinely detected in Si molecular-beam epitaxy (MBE) when using standard MBE cleaning schemes. The influence of the wet chemical precleaning as well as of the in situ cleaning is investigated with respect to this effect: whenever chemical precleaning results in a hydrophilic Si surface, interfacial p-type doping due to B contamination of 1012 cm−2 is detected, whereas for hydrophobic Si surfaces the B contamination is reduced by a factor of about 50. Concerning the in situ cleaning, a reduction of the preheating temperature TH correlates with a decrease of p-type doping for hydrophilic cleaned samples, though the chemical B contamination is independent of TH, i.e., the in situ preheating induces an electrical activation of the B contamination.

Impact of Ba to Si deposition rate ratios during molecular beam epitaxy on carrier concentration and spectral response of BaSi2 epitaxial films

“…It is reported that p-type doping due to B contamination is routinely detected in Si MBE when using standard MBE cleaning schemes. 46,47 The influence of the wet chemical precleaning as well as of the in situ thermal cleaning in the ultra-high vacuum was investigated with respect to this effect. 46 We cannot detect such a small B concentration of the order of 10 15 cm À3 by secondary ion mass spectrometry (SIMS), which is much smaller than the SIMS detection limit of B in BaSi 2 .…”

Secondary ion mass spectroscopy ultrashallow depth profiling for Si/Si1−xGex/Si heterojunction bipolar transistors

“…Boron interfacial contamination, resulting from residual substrate contamination ͑or from the in situ cleaning procedure before growth͒ is a well-known problem for MBE. 26,27 It can result in inhomogeneous segregation effects 27 and/or diffusional broadening of the interfacial peak which can disturb the optimized dopant profiles. Therefore, characterization of the contamination is necessary.…”

Carbon-Nanotube-Enhanced Thermal Contactor in Low Contact Pressure Region

“…In this experiment, the β-FeSi 2 balls were found to be located in the p-Si layer, which was confirmed by electron beam induced current (EBIC) mea-surements. This is because boron accumulation occurs at the substrate after cleaning by the RCA method, 22) and the Si overlayer is lightly doped p-Si (p∼2×10 16 cm −3 ). Figure 2 shows the PL spectra measured at 12.5 K with a pumping power of 25 mW for (a) the Si substrate, (b) the annealed sample, and (c) the 200-Å-, (d)100-Å-and (e) 30-A-thick-layer-deposited ball samples.…”