Fabrication of p+ contact by thermally induced solid state regrowth of Al on p-type Ge crystal. (January 2021)

• Record Type: Journal Article
• Authors: Ghosh, Manoranjan; Pitale, Shreyas; Singh, S.G.; Manasawala, Husain; Karki, Vijay; Singh, Manish; Singh, Kulwant; Patra, G.D.; Sen, Shashwati
• Is Part Of: Materials science in semiconductor processing. Volume 121(2021)
• Publication Date: 2021-01
• Subjects: Carrier concentration -- Depth profile -- Ge crystal -- p-type contact -- Sheet resistance -- Solid state regrowth; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2020.105350
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: Formation of p + contact on germanium is important for its applications in diode detector and other electronic devices. In this work, thermally deposited Al on Ge crystal is annealed at 350 °C followed by slow cooling for solid-state regrowth of Al-Ge p + contact on Ge . Depth profile analysis by secondary ion mass spectrometry (SIMS) is carried out to investigate the occurrence of Al and Ge along the depth of the regrown Al-Ge layer. Evidence of regrowth is observed due to inter-diffusion of both Ge and Al across the layers although Ge diffusion in Al layer is found to be more prevalent. Thickness of the evaporated Al layer is varied to understand the diffusion profile of Al, Ge and estimate the depth of Al incorporation in Ge crystal underneath. Hall measurement at different depth of Al-Ge regrown layer reveals that Al impurity induces p + doping in p-type Ge and its concentration gradually reduces towards the Ge crystal. Top surface of the Al-Ge layer exhibits lowest sheet resistance that varies with the thickness of the as deposited Al layer. Highlights: Rugged p + electrical contact on p-type Ge crystal is fabricated by solid state regrowth of Al deposited on Ge. Diffusion of both Ge and Al across the Al/Ge interface is observed after annealing at 350 °C followed by slow cooling. Depth profiling by secondary ion mass spectrometry is performed to estimate the diffusion length of Ge in Al and vice versa. Thickness of the as deposited Al layer is varied to control the depth of Al-Ge regrown layer. Al impurity induces p + doping in p-type Ge and its concentration gradually reduces towards the Ge crystal.