Thermally Driven Crossover from Indirect toward Direct Bandgap in 2D Semiconductors: MoSe2 versus MoS2
Top Cited Papers
- 25 October 2012
- journal article
- letter
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 12 (11), 5576-5580
- https://doi.org/10.1021/nl302584w
Abstract
Layered semiconductors based on transition-metal chalcogenides usually cross from indirect bandgap in the bulk limit over to direct bandgap in the quantum (2D) limit. Such a crossover can be achieved by peeling off a multilayer sample to a single layer. For exploration of physical behavior and device applications, it is much desired to reversibly modulate such crossover in a multilayer sample. Here we demonstrate that, in a few-layer sample where the indirect bandgap and direct bandgap are nearly degenerate, the temperature rise can effectively drive the system toward the 2D limit by thermally decoupling neighboring layers via interlayer thermal expansion. Such a situation is realized in few-layer MoSe2, which shows stark contrast from the well-explored MoS2 where the indirect and direct bandgaps are far from degenerate. Photoluminescence of few-layer MoSe2 is much enhanced with the temperature rise, much like the way that the photoluminescence is enhanced due to the bandgap crossover going from the bulk to the quantum limit, offering potential applications involving external modulation of optical properties in 2D semiconductors. The direct bandgap of MoSe2, identified at 1.55 eV, may also promise applications in energy conversion involving solar spectrum, as it is close to the optimal bandgap value of single-junction solar cells and photoelechemical devices.Keywords
This publication has 32 references indexed in Scilit:
- Magnetic properties of MoS2: Existence of ferromagnetismApplied Physics Letters, 2012
- High Efficiency Graphene Solar Cells by Chemical DopingNano Letters, 2012
- $\hbox{MoS}_{2}$ Dual-Gate MOSFET With Atomic-Layer-Deposited $\hbox{Al}_{2}\hbox{O}_{3}$ as Top-Gate DielectricIEEE Electron Device Letters, 2012
- Ambipolar MoS2 Thin Flake TransistorsNano Letters, 2012
- Single-Layer MoS2PhototransistorsACS Nano, 2011
- Fabrication of Single‐ and Multilayer MoS2 Film‐Based Field‐Effect Transistors for Sensing NO at Room TemperatureSmall, 2011
- High-frequency, scaled graphene transistors on diamond-like carbonNature, 2011
- An ultrasensitive and low-cost graphene sensor based on layer-by-layer nano self-assemblyApplied Physics Letters, 2011
- Single-layer MoS2 transistorsNature Nanotechnology, 2011
- The electronic properties of grapheneReviews of Modern Physics, 2009