Population inversion in monolayer and bilayer graphene

被引：51

作者：

Gierz, Isabella ^{[1
]}

Mitrano, Matteo ^{[1
]}

Petersen, Jesse C. ^{[2
]}

Cacho, Cephise ^{[3
]}

Turcu, I. C. Edmond ^{[3
]}

Springate, Emma ^{[3
]}

Stoehr, Alexander ^{[4
]}

Koehler, Axel ^{[4
]}

Starke, Ulrich ^{[4
]}

Cavalleri, Andrea ^{[1
,2
]}

机构：

[1] Max Planck Inst Struct & Dynam Matter, D-22761 Hamburg, Germany

[2] Univ Oxford, Dept Phys, Clarendon Lab, Oxford OX1 2JD, England

[3] STFC Rutherford Appleton Lab, Cent Laser Facil, Harwell, Berks, England

[4] Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany

来源：

JOURNAL OF PHYSICS-CONDENSED MATTER | 2015年 / 27卷 / 16期

关键词：

graphene; time- and angle-resolved photoemission spectroscopy; hot carrier dynamics; CARRIER MULTIPLICATION; ULTRAFAST; RELAXATION; DYNAMICS;

D O I：

10.1088/0953-8984/27/16/164204

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

The recent demonstration of saturable absorption and negative optical conductivity in the Terahertz range in graphene has opened up new opportunities for optoelectronic applications based on this and other low dimensional materials. Recently, population inversion across the Dirac point has been observed directly by time- and angle-resolved photoemission spectroscopy (tr-ARPES), revealing a relaxation time of only similar to 130 femtoseconds. This severely limits the applicability of single layer graphene to, for example, Terahertz light amplification. Here we use tr-ARPES to demonstrate long-lived population inversion in bilayer graphene. The effect is attributed to the small band gap found in this compound. We propose a microscopic model for these observations and speculate that an enhancement of both the pump photon energy and the pump fluence may further increase this lifetime.

引用

页数：8

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