CMOS Compatible in-Situ N-Type Doping of Ge Using New Generation Doping Agents P(MH3)3 and As(MH3)3 (M=Si, Ge)

Abstract

New in-situ methods have been developed to dope Ge-on-Si films with P and As using reactions of novel compounds P(MH3)3 and As(MH3)3 (M=Si, Ge) and UHV-CVD and molecular source epitaxy methods. In these experiments Ge3H8, Ge4H10 hydrides were used to deposit intrinsic Ge layers on Si(100) to produce i-Ge/Si(100) platforms upon which the n-Ge layers were grown at ultra-low temperatures of 300-330°C. The resultant n-Ge/i-Ge/Si(100) samples exhibited device quality crystallinity and defect-free microstructures as evidenced by XTEM. Infrared spectroscopic ellipsometry (IRSE) and Hall revealed carrier concentrations, mobilities and resistivities that are on par with values observed in bulk Ge. SIMS gave flat dopant profiles and abrupt transitions at the n/i interfaces. The highest carrier concentration was achieved in As doped samples at 8.44×1019 cm-3 and the lowest resistivity was observed in P doped samples at 4.2×10-4 Ω∙cm. Comparison between IRSE and SIMS data revealed near full activation (>80%) of the absolute dopant concentrations in the range of 1×1020 cm-3. The methods reported here have the potential for applications in group-IV semiconductor technologies that require high doping levels, low resistivities and shallow junction depths.