Charge collection efficiency of Pt vs. Mg contacts on semi-insulating GaAs

Authors :: D. Kindl
Pavel Hubík
František Dubecký
Matúš Dubecký
Bohumír Zaťko
E. Gombia
V. Kolesár
Source :: Applied surface science 467-468 (2019): 1219–1225. doi:10.1016/j.apsusc.2018.10.164, info:cnr-pdr/source/autori:Dubecky F.; Zatko B.; Kolesar V.; Kindl D.; Hubik P.; Gombia E.; Dubecky M./titolo:Charge collection efficiency of Pt vs. Mg contacts on semi-insulating GaAs/doi:10.1016%2Fj.apsusc.2018.10.164/rivista:Applied surface science/anno:2019/pagina_da:1219/pagina_a:1225/intervallo_pagine:1219–1225/volume:467-468
Publication Year :: 2019
Publisher :: Elsevier BV, 2019.
Abstract: A comparative study of diode structures based on semi-insulating (SI) GaAs with evaporated Mg vs. Pt contacts is presented. Electric field strength in the vicinity of the contacts is inferred from the detection of α-particles emitted from 241Am radioisotope. It is shown that at zero bias, the structure with Mg-based contacts (MgO/SI GaAs) gives comparatively small signal implying an ohmic behaviour. Contrary, the structure with Pt contacts reveals presence of a non-negligible electric field near the contacts at zero bias voltage, thus indicating presence of a sizeable space charge region near the interface. The results are supplemented by insights from atomistic electronic structure modeling of idealized GaAs/Pt vs. GaAs/Mg and GaAs/MgO interfaces.