Monolayer excitonic laser

Abstract

Recently, two-dimensional (2D) materials have opened a new paradigm for fundamental physics explorations and device applications. Unlike gapless graphene, monolayer transition metal dichalcogenide (TMDC) has new optical functionalities for next generation ultra-compact electronic and opto-electronic devices. When TMDC crystals are thinned down to monolayers, they undergo an indirect to direct bandgap transition 1, 2 , making it an outstanding 2D semiconductor [1][2][3][4][5] . Unique electron valley degree of freedom [6][7][8][9] , strong light matter interactions 10 and excitonic effects were observed [11][12][13] . Enhancement of spontaneous emission has been reported on TMDC monolayers integrated with photonic crystal 14,15 and distributed Bragg reflector microcavities 16,17 .However, the coherent light emission from 2D monolayer TMDC has not been demonstrated, mainly due to that an atomic membrane has limited material gain volume and is lack of optical mode confinement. Here, we report the first realization of 2D excitonic laser by embedding monolayer tungsten disulfide (WS 2 ) in a microdisk resonator. Using a whispering gallery mode (WGM) resonator with a high quality factor and optical confinement, we observed bright excitonic lasing in visible wavelength. The Si 3 N 4 /WS 2 /HSQ sandwich configuration provides a strong feedback and mode overlap with monolayer gain. This demonstration of 2D excitonic laser marks a major step towards 2D on-chip optoelectronics for high performance optical communication and computing applications.

High Luminescence Efficiency in MoS2 Grown by Chemical Vapor Deposition

“…Hence, defects in optoelectronic devices translate into a lowering of the efficiency for light-emitting diodes (LEDs) and an increase in the threshold current for solid-state lasers. 21 The passivation of interfaces has been heavily investigated in all semiconductors. To realize high-performance silicon transistors, the Si/SiO 2 interface is annealed in forming gas.…”

Ultrathin MoO2 nanosheets with good thermal stability and high conductivity

“…Our In recent years, 2D materials have aroused great interest as potential building blocks for a variety of fundamental optoelectronic components. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] To date, various 2D materials have been synthesized, including well-known graphene, 15 transition metal dichalcogenides, 16 antimonene, 17 black phosphorus, 18 Mo 2 C, 19 BN, 20 and so on, but some of which face very challenging in various optical and electronic applications due to zero-bandgap, low conductivity, or severe instability in air. In order to address this problem, it is urgent to develop a new material with a good stability and high conductivity.…”

Nonvolatile MoS2 field effect transistors directly gated by single crystalline epitaxial ferroelectric

“…Multilayer MoS2 flakes were chosen for high channel current. The selected MoS2 flakes were transferred onto PZT substrates via dry cutting transfer process 18 . AFM was used to measure the thickness and uniformity of the flakes after transfer.…”