Upadhyay Bhuvan, Sharma Rahul, Maity Dipak, Narayan Tharangattu N, Pal Suman Kalyan
School of Physical Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh, 175075, India.
Advanced Materials Research Center, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh, 175075, India.
Nanoscale. 2023 Oct 20;15(40):16344-16353. doi: 10.1039/d3nr03337f.
Substitutional doping is a most promising approach to manipulate the electronic and optical properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs). In addition to inducing magnetism, vanadium (V) doping can lead to semiconductor-metal transition in TMDCs. However, the dynamics of charge carriers that governs the optoelectronic properties of doped TMDCs has been rarely revealed. In this work, we have investigated the dynamics of photocarriers in pristine and V-doped monolayer (ML) MoS. Comparison of the transient absorption (TA) spectra of ML MoS with lightly (≤1%) and heavily (3.62%) V-doped MoS infers the induction of additional energy states in the doped materials giving rise to new low energy bleach features in the TA spectra. The quasiparticle band structure of MoS is found to disappear at sufficiently high V doping due to the presence of impurity bands. An attempt has also been made to study the manipulation of the carrier lifetime with V doping in MoS. Our TA kinetic measurements suggest that the decay kinetics of the carriers becomes slower with increasing doping percentage and at a higher doping level the carriers survive for a much longer time compared to pristine MoS. Furthermore, we have identified a new electronic transition (NET) in heavily V-doped MoS at high pump fluences.
替代掺杂是一种最具前景的方法，用于调控二维（2D）过渡金属二硫属化物（TMDCs）的电子和光学性质。除了诱导磁性外，钒（V）掺杂还可导致TMDCs中的半导体-金属转变。然而，支配掺杂TMDCs光电性质的载流子动力学很少被揭示。在这项工作中，我们研究了原始和V掺杂单层（ML）MoS中光载流子的动力学。比较轻度（≤1%）和重度（3.62%）V掺杂MoS的ML MoS的瞬态吸收（TA）光谱，推断出掺杂材料中诱导出额外的能态，从而在TA光谱中产生新的低能漂白特征。由于杂质带的存在，发现MoS的准粒子能带结构在足够高的V掺杂下消失。我们还尝试研究了V掺杂对MoS中载流子寿命的调控。我们的TA动力学测量表明，随着掺杂百分比的增加，载流子的衰减动力学变得更慢，并且在更高的掺杂水平下，与原始MoS相比，载流子存活的时间长得多。此外，我们在高泵浦通量下的重度V掺杂MoS中识别出一种新的电子跃迁（NET）。
