Hummon, M. R. ; Stollenwerk, A. J. ; Narayanamurti, V. ; Anikeeva, P. O. ; Panzer, M. J. ; Wood, V. ; Bulovic, V. (2010) Measuring charge trap occupation and energy level in CdSe/ZnS quantum dots using a scanning tunneling microscope Physical Review B, 81 (11). 115439_1-115439_8. ISSN 1098-0121
|
PDF
- Publisher Version
749kB |
Official URL: http://prb.aps.org/abstract/PRB/v81/i11/e115439
Related URL: http://dx.doi.org/10.1103/PhysRevB.81.115439
Abstract
We use a scanning tunneling microscope to probe single-electron charging phenomena in individual CdSe/ZnS (core/shell) quantum dots (QDs) at room temperature. The QDs are deposited on top of a bare Au thin film and form a double-barrier tunnel junction (DBTJ) between the tip, QD, and substrate. Analysis of room-temperature hysteresis in the current-voltage (IV) tunneling spectra, is consistent with trapped charge(s) presenting an additional potential barrier to tunneling, a measure of the Coulomb blockade. The paper describes the first direct electrical measurement of the trap-state energy on individual QDs. Manipulation of the charge occupation of the QD, verified by measuring the charging energy, (61.4±2.4) meV, and analysis of the DBTJ, show trap states ~1.09 eV below the QD conduction-band edge. In addition, the detrapping time, a measure of the tunneling barrier thickness, is determined to have an upper time limit of 250 ms. We hypothesize that the charge is trapped in a quantum-dot surface state.
Item Type: | Article |
---|---|
Source: | Copyright of this article belongs to American Physical Society. |
ID Code: | 30621 |
Deposited On: | 23 Dec 2010 13:02 |
Last Modified: | 17 May 2016 13:14 |
Repository Staff Only: item control page