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We investigate phosphorus in-situ doping characteristics in germanium (Ge) during epitaxial growth by spreading resistance profiling analysis. In addition, we present an accurate model for the kinetics of the diffusion in the in-situ process,modeling combined growth and diffusion events. The activation energy and pre-exponential factor for phosphorus (P) diffusion are determined to be 1.91 eV and 3.75 105 cm2/s. These results show that P in-situ doping diffusivity is low enough to form shallow junctions for high Arsenic (As) is known to have low solid solubility and high tion, since its high e formation of nþ has relatively high fusivity, has been achieve chemical implant damages hindering forma-s [6e9], caused by iffusion of P leads contrast to these que avoids any sions, and conse-quently provides fairly shallow junctions while offering high elec-trically activated concentrations [10,11] at low processing temperatures. We recently demonstrated an abrupt and box-shaped high quality Ge nþ/p junction diode with in-situ doping technique the result of which is reported elsewhere [12]. In order to estimate accurately junction depth and shapewhen forming n-type shallow junctions in Ge, accurate dopant diffusion modeling is required. Although there are a few theoretical studies about P diffusion in Ge [14,15], by simulations, such analyses are performe