TY - JOUR
T1 - Characterization of low-resistance ohmic contacts to a two-dimensional electron gas in a GaAs/AlGaAs heterostructure
AU - Javaid Iqbal, Muhammad
AU - Reuter, Dirk
AU - Wieck, Andreas Dirk
AU - Van Der Wal, Caspar
N1 - Funding Information:
We thank B. Wolfs, J. Holstein and M. de Roosz for technical assistance. A.D.W. acknowledges financial support from the DFG-TRR160, BMBF - Q.Link.X 16KIS0867, and the DFH/UFA CDFA-05-06. M.J.I. acknowledges a scholarship from the Higher Education Commission of Pakistan.
Publisher Copyright:
© EDP Sciences, 2020.
PY - 2020/2/1
Y1 - 2020/2/1
N2 - The study of electron transport in low-dimensional systems is of importance, not only from a fundamental point of view, but also for future electronic and spintronic devices. In this context heterostructures containing a two-dimensional electron gas (2DEG) are a key technology. In particular GaAs/AlGaAs heterostructures, with a 2DEG at typically 100 nm below the surface, are widely studied. In order to explore electron transport in such systems, low-resistance ohmic contacts are required that connect the 2DEG to macroscopic measurement leads at the surface. Here we report on designing and measuring a dedicated device for unraveling the various resistance contributions in such contacts, which include pristine 2DEG series resistance, the 2DEG resistance under a contact, the contact resistance itself, and the influence of pressing a bonding wire onto a contact. We also report here a recipe for contacts with very low resistance values that remain below 10 ω for annealing times between 20 and 350 s, hence providing the flexibility to use this method for materials with different 2DEG depths. The type of heating, temperature ramp rate and gas forming used for annealing is found to strongly influence the annealing process and hence the quality of the resulting contacts.
AB - The study of electron transport in low-dimensional systems is of importance, not only from a fundamental point of view, but also for future electronic and spintronic devices. In this context heterostructures containing a two-dimensional electron gas (2DEG) are a key technology. In particular GaAs/AlGaAs heterostructures, with a 2DEG at typically 100 nm below the surface, are widely studied. In order to explore electron transport in such systems, low-resistance ohmic contacts are required that connect the 2DEG to macroscopic measurement leads at the surface. Here we report on designing and measuring a dedicated device for unraveling the various resistance contributions in such contacts, which include pristine 2DEG series resistance, the 2DEG resistance under a contact, the contact resistance itself, and the influence of pressing a bonding wire onto a contact. We also report here a recipe for contacts with very low resistance values that remain below 10 ω for annealing times between 20 and 350 s, hence providing the flexibility to use this method for materials with different 2DEG depths. The type of heating, temperature ramp rate and gas forming used for annealing is found to strongly influence the annealing process and hence the quality of the resulting contacts.
UR - http://www.scopus.com/inward/record.url?scp=85083630231&partnerID=8YFLogxK
U2 - 10.1051/epjap/2020190202
DO - 10.1051/epjap/2020190202
M3 - Article
AN - SCOPUS:85083630231
SN - 1286-0050
VL - 89
JO - The European Physical Journal Applied Physics
JF - The European Physical Journal Applied Physics
IS - 2
M1 - 20101
ER -