Title :
Extremely low-resistance nonalloyed ohmic contacts on molecular beam epitaxially grown p-type Ge
Author :
Unlu, M.S. ; Strite, S. ; Adomi, K. ; Gao, G.B. ; Morkoc, H.
Author_Institution :
Mater. Sci. Lab., Illinois Univ., Urbana, IL, USA
Abstract :
Extremely low-resistance nonalloyed ohmic contacts have been formed on p-type Ge grown on GaAs by molecular beam epitaxy as part of a research effort into GaAs/Ge heterojunction devices. Using evaporated Ti/Al metallisation, specific contact resistances well below 1*10-8 Omega cm2 were achieved for heavily doped Ge (p>1*1019 cm-3). The investigated Ge layers were grown as the base region of AlGaAs/Ge/GaAs HBTs. The influence of the low base resistance on the high-frequency performance of HBTs was studied by simulations.
Keywords :
III-V semiconductors; aluminium; aluminium compounds; contact resistance; elemental semiconductors; gallium arsenide; germanium; heterojunction bipolar transistors; molecular beam epitaxial growth; ohmic contacts; semiconductor growth; semiconductor junctions; semiconductor technology; semiconductor-metal boundaries; titanium; GaAs/Ge heterojunction devices; Ge on GaAs; Ge-Ti-Al ohmic contacts; HBT; heavily doped Ge; high-frequency performance; low base resistance; low-resistance nonalloyed ohmic contacts; molecular beam epitaxy; p-type Ge base; semiconductors; specific contact resistances;
Journal_Title :
Electronics Letters
DOI :
10.1049/el:19900060
