A Two-Dimensional Electron Gas as a Sensitive Detector for Time-Resolved Tunneling Measurements on Self-Assembled Quantum Dots

Abstract

A two-dimensional electron gas (2DEG) situated nearby a single layer of self-assembled quantum dots (QDs) in an inverted high electron mobility transistor (HEMT) structure is used as a detector for time-resolved tunneling measurements. We demonstrate a strong influence of charged QDs on the conductance of the 2DEG which allows us to probe the tunneling dynamics between the 2DEG and the QDs time resolved. Measurements of hysteresis curves with different sweep times and real-time conductance measurements in combination with an boxcar-like evaluation method enables us to unambiguously identify the transients as tunneling events between the s- and p-electron QD states and the 2DEG and rule out defect-related transients.

GaSb/GaAs quantum dot formation and demolition studied with cross-sectional scanning tunneling microscopy

“…Fast carrier capture and long charge storage capabilities of type-II QDs suggest their potential application in memory devices. 1,2 Recent studies have shown that the use of a two-dimensional electron 3,4 or hole 5,6 gas in combination with QDs allows writing and reading information, demonstrating the basic operations required in memory devices.…”

Direct fabrication and characterization of vertically stacked Graphene/h-BN/Graphene tunnel junctions

“…However, one lesser-known device that utilized 2DEGs is a tunnel junction consisting of two such gases [2,3], realizing 2D-2D tunneling. Previous studies of 2D-2D tunneling were conducted on coupled electron gas systems in two closely placed quantum wells in AlGaAs/GaAs heterostructures [3,4]. In the case of unequal doping of the 2DEGs, it has been shown experimentally that, at a voltage bias corresponding to aligned band structures of the 2D systems, a sharp peak in the tunnel current occurs [1,[5][6][7][8].…”

Sweeping-rate-dependent photocurrent of GaAs Schottky diode with strain relaxed InAs quantum dots

“…Some groups used the current detection of the two-dimensional electron gas (2DEG) layer to probe the carrier storage in the QDs. [16][17][18][19][20] Some groups mentioned the Coulomb blockade caused by charged QDs may influence the current. 21,22) In any cases, the current of a device is influenced by the embedded InAs QDs in several mechanism.…”