Accumulation mode GaAs/AlGaAs 2D electron system with independent control of the channel and contact resistance
Abstract
Semiconductor-insulator-semiconductor FETs (SISFETs) are an attractive alternative to modulation doped (MD) GaAs/AlGaAs systems. GaAs SISFETs consist of epitaxially grown layers of GaAs then AlGaAs capped with a degenerately doped GaAs layer. The cap acts as an in situ, over-all top-gate which attracts carriers to the GaAs/AlGaAs interface. The MBE grown top-gate eliminates scattering and charge-noise from surface states and unlike Schottky gates, there is no strain between the gate and insulating AlGaAs layer due to similar thermal expansion rates. The absence of a doping layer improves carrier mobility (μ) at low densities (ns) since in shallow MD devices the doping layer creates an additional long-range random impurity potential. For this reason SISFET devices improve μ at low ns. However in the low ns regime the high contact resistance dominates the device resistance, which can limit electrical transport measurements. We fabricate a GaAs 2D electron SISFET with dual-gate architecture to independently control the contact and channel resistance. We characterize our device using standard low-temperature electrical transport measurements. The 2D ns could be varied from 0 . 1 - 3 ×1011 cm-2 with a μ of up to 9 ×106 cm2V-1s-1 .
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2014
- Bibcode:
- 2014APS..MARS45015M