Highly scaled nanoelectronics requires effective channel doping above 5× 10 19 cm− 3 together with ohmic contacts with extremely low specific contact resistivity. Nowadays, Ge becomes very attractive for modern optoelectronics due to the high carrier mobility and the quasi-direct bandgap, but n-type Ge doped above 5× 10 19 cm− 3 is metastable and thus difficult to be achieved. In this letter, we report on the formation of low-resistivity ohmic contacts in highly n-type doped Ge via non-equilibrium thermal processing consisting of millisecond-range flash lamp annealing. This is a single-step process that allows for the formation of a 90 nm thick NiGe layer with a very sharp interface between NiGe and Ge. The measured carrier concentration in Ge is above 9× 10 19 cm− 3 with a specific contact resistivity of 1.2× 10− 6 Ω cm 2. Simultaneously, both the diffusion and the electrical deactivation of P are fully suppressed.
4 Oct 2017
Volume: 32 Issue: 11 Pages: 115006
Semiconductor Science and Technology