Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 60: III-V Semiconductors (no Nitrides)
HL 60.2: Vortrag
Mittwoch, 9. März 2016, 15:00–15:15, H13
Next generation gating: Prepatterned back gates implemented into the growth of ultra-high mobility GaAs/AlGaAs heterostructures — •Matthias Berl1, Lars Tiemann1, Werner Dietsche1, Werner Wegscheider1, and Helmut Karl2 — 1ETH Zürich, 8093 Zürich, Switzerland — 2Universität Augsburg, 86159 Augsburg, Germany
Electrostatic gating of semiconductors is of fundamental interest, because it allows to modify the inherent electrical properties of the semiconducting material. Typically evaporated top gates are used after the heterostructure growth, because their processing is more flexible and can be adjusted at will. However, top gates are not always the best solution. Due to the Schottky barrier, top gates are often limited in the gating range and they can be obstructive for optical penetration.
We have developed a method to implement patterned back gate structures into the growth of high mobility MBE heterostructures. The back gate structures are defined by local oxygen implantation into a silicon doped GaAs epilayer grown on top of the insulating substrate. The oxygen implantation suppresses the conductance without affecting the surface quality, allowing for high quality heterostructure growth. First measurements have demonstrated a wide range of tunability (2*1010 cm−2 to 4.4*1011 cm−2) for a two-dimensional electron gas grown on an implantation patterned substrate with mobilities exceeding 20*10−6 cm2/Vs.