Phonon Lifetimes in Boron‐Isotope‐Enriched Graphene‐ Hexagonal Boron Nitride Devices
Phonon Lifetimes in Boron‐Isotope‐Enriched Graphene‐ Hexagonal Boron Nitride Devices
复制标题
硼的声子寿命——同位素——富集石墨烯——六方氮化硼器件
DOI：
10.1002/pssr.202200030
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Sandhu, Arvinder
中科院分区：
文献类型：
--
作者：
Brasington, Alexandra;Liu, Song;Taniguchi, Takashi;Watanabe, Kenji;Edgar, James H.;LeRoy, Brian J.;Sandhu, Arvinder
使用六方氮化硼（hBN）作为石墨烯的衬底显示出更快的载流子冷却，这使得它成为高功率石墨烯基器件的理想选择。然而，尚未探索使用硼同位素富集的hBN的效果。在本文中，飞秒泵浦-探测光谱用于测量和比较具有硼同位素（20%10B和80%11B）的自然分布的hBN和富集至100%10B和11B的hBN的石墨烯-hBN异质结构中的光激发载流子的时间动力学。对于具有同位素纯hBN底物的系统，载体冷却更快，冷却因子为1.7倍。弛豫时间的这种差异源于石墨烯中的载流子与hBN声子模式之间的界面耦合。结果表明，hBN衬底的硼同位素纯度可以帮助减少限制石墨烯器件中的冷却的热声子瓶颈。
Using hexagonal boron nitride (hBN) as a substrate for graphene has shown faster carrier cooling which makes it ideal for high‐power graphene‐based devices. However, the effect of using boron‐isotope‐enriched hBN has not been explored. Herein, femtosecond pump‐probe spectroscopy is utilized to measure and compare the time dynamics of photo‐excited carriers in graphene‐hBN heterostructures for hBN with the natural distribution of boron isotopes (20%10B and 80%11B) and hBN enriched to 100%10B and11B. The carriers cool down faster for systems with isotopically pure hBN substrates by a factor of ≈1.7 times. This difference in relaxation times arises from the interfacial coupling between carriers in graphene and the hBN phonon modes. The results show that the boron isotopic purity of the hBN substrate can help to reduce the hot phonon bottleneck that limits the cooling in graphene devices.