In situ ohmic contact formation for n-type Ge via non-equilibrium processing. (4th October 2017)

• Record Type: Journal Article
• Authors: Prucnal, S; Frigerio, J; Napolitani, E; Ballabio, A; Berencén, Y; Rebohle, L; Wang, M; Böttger, R; Voelskow, M; Isella, G; Hübner, R; Helm, M; Zhou, S; Skorupa, W
• Is Part Of: Semiconductor science and technology. Volume 32:Number 11(2017:Nov.)
• Publication Date: 2017-10-04
• Subjects: germanium -- flash lamp annealing -- ion implantation -- NiGe -- ohmic contact; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/aa8b2f
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: 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.