CNR ExploRA

Articolo in rivista, 2017, ENG, 10.1063/1.4973461

Low temperature deactivation of Ge heavily n-type doped by ion implantation and laser thermal annealing

Milazzo R.; Impellizzeri G.; Piccinotti D.; De Salvador D.; Portavoce A.; La Magna A.; Fortunato G.; Mangelinck D.; Privitera V.; Carnera A.; Napolitani E.

CNR-IMM MATIS, Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, Padova, 35131, , , Italy; CNR-IMM MATIS, Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, Padova, 35131, , , Italy; CNR-IMM, Via S. Sofia 64, Catania, 95123, , Italy; IM2NP, CNRS-Universités d'Aix-Marseille et de Toulon, Case 142, Marseille Cedex 20, 13397, , France; CNR-IMM, Z.I. VIII Strada 5, Catania, 95121, , Italy; CNR-IMM, Via del Fosso del Cavaliere 100, Roma, 00133, , Italy

Heavy doping of Ge is crucial for several advanced micro- and optoelectronic applications, but, at the same time, it still remains extremely challenging. Ge heavily n-type doped at a concentration of 1 × 10cm by As ion implantation and melting laser thermal annealing (LTA) is shown here to be highly metastable. Upon post-LTA conventional thermal annealing As electrically deactivates already at 350 °C reaching an active concentration of ~4 × 10cm. No significant As diffusion is detected up to 450 °C, where the As activation decreases further to ~3 × 10cm. The reason for the observed detrimental deactivation was investigated by Atom Probe Tomography and in situ High Resolution X-Ray Diffraction measurements. In general, the thermal stability of heavily doped Ge layers needs to be carefully evaluated because, as shown here, deactivation might occur at very low temperatures, close to those required for low resistivity Ohmic contacting of n-type Ge.

Applied physics letters 110