Gabriel G. Maia

7 Questions 2 Answers 0 Followers

Questions related from Gabriel G. Maia

Architecture of ohmic contacts for a top-gated hall bar. Can comb-shaped contact under the top-gate improve contact resistance?

Greetings. I am trying to get lower contact resistance in a Hall bar made of a Ge quantum well sandwiched between two SiGe layers. The ohmic metal is Al. After addressing issues like the removal...

15 July 2021 7,273 4 View

What parameters of Ar plasma are appropriate for native oxide cleaning of Si, SiGe and Ge surfaces?

Greetings. I have a mesa structure with a top Si layer and the side walls have SiGe and a Ge quantum well exposed. I want to make Al contacts to this well but native oxides prevent good ohmic...

11 June 2021 9,560 2 View

What is the influence of a Hall bar geometry on transport measurements?

Greetings. I have been trying to fabricate a Hall bar on a SiGe/Ge heterostructure for transport measurements and so far my devices have failed to show ohmic behaviour at low temperatures. I have...

13 May 2021 4,718 1 View

Is it normal for Au layers deposited at different times to have bad adherence?

Greetings. Recently I have noticed a problem with my wire bonding. When I deposit 20nm of Ti for adherence (on a SiGe layer of a heterostructured sample) and then 200nm of Au, the wire bonding...

06 November 2020 2,895 0 View

What is the thickness profile of the deposition of overlapping layers of thin films?

Greetings. When I deposit a thin film layer, say a block of metal on top of a mesa structure, and then deposit another layer which covers the original one only partially and extends to the mesa,...

07 October 2020 6,820 3 View

Does gold diffusion in Si during annealing change the resistivity of the gold electrode?

Greetings. I have struggled with Al ohmic contacts between a Ge Hall bar and Au electrodes. I thought the problem was the Ge/Al interface (increased resistance due to native oxide formation on...

26 June 2020 5,811 2 View

How can I obtain good Aluminium/Germanium ohmic contacts at low temperatures?

Greetings. I am having trouble achieving ohmic contacts between Aluminium and Germanium that work at low temperatures. My contacts behave ohmically at room temperature, with a relatively high...

10 January 2020 737 4 View