Field-effect-induced two-dimensional electron gas utilizing modulation-doped ohmic contacts

Sumit Mondal,Geoffrey C Gardner,John D Watson,Saeed Fallahi,Amir Yacoby,Michael J Manfra

doi:10.1016/j.ssc.2014.08.011

Abstract

Modulation-doped AlGaAs/GaAs heterostructures are utilized extensively in the study of quantum transport in nanostructures, but charge fluctuations associated with remote ionized dopants often produce deleterious effects. Electric field-induced carrier systems offer an attractive alternative if certain challenges can be overcome. We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate reliable low-resistance contacts. A high quality two-dimensional electron gas is induced by a field-effect and is tunable over a wide range of density. Device design, fabrication, and low temperature (T=0.3K) transport data are reported.

Highlights

We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate reliable lowresistance contacts
The most widely studied device is the heterostructure-insulated-gate field-effect transistor (HIGFET), in which a highly-conducting n+ GaAs gate is grown on top of an insulating AlxGa1−xAs barrier layer by molecular beam epitaxy (MBE) [14-16, 18, 22]
HIGFET fabrication requires placing ohmic contacts in intimate contact with the primary AlGaAs/GaAs interface where the 2DEG will reside without shorting the ohmic contact to the n+ GaAs gate [17, 18]

Summary

Introduction

“Field-Effect-Induced Two-Dimensional Electron Gas Utilizing Modulation-Doped Ohmic Contacts.” Solid State Communications 197 (November): 20–24. Field-effect-induced two-dimensional electron gas utilizing modulation doping for improved ohmic contacts We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate reliable lowresistance contacts.

Results

Conclusion