Broadband micro-transient absorption spectroscopy enabled by improved lock-in amplification.

Recent breakthroughs in material development have increased the demand for characterization methods capable of probing nanoscale features on ultrafast time scales. As the sample reduces to atomically thin levels, an extremely low-level signal limits the feasibility of many experiments. Here, we present an affordable and easy-to-implement solution to expand the maximum sensitivity of lock-in detection systems used in transient absorption spectroscopy by multiple orders of magnitude.

Reversible Photoluminescence Tuning by Defect Passivation via Laser Irradiation on Aged Monolayer MoS.

Atomically thin (1L)-MoS emerged as a direct band gap semiconductor with potential optical applications. The photoluminescence (PL) of 1L-MoS degrades due to aging-related defect formation. The passivation of these defects leads to substantial improvement in optical properties.

Dense Electron-Hole Plasma Formation and Ultralong Charge Lifetime in Monolayer MoS via Material Tuning.

Many-body interactions in photoexcited semiconductors can bring about strongly interacting electronic states, culminating in the fully ionized matter of electron-hole plasma (EHP) and electron-hole liquid (EHL). These exotic phases exhibit unique electronic properties, such as metallic conductivity and metastable high photoexcitation density, which can be the basis for future transformative applications. However, the cryogenic condition required for its formation has limited the study of dense plasma phases to a purely academic pursuit in a restricted parameter space.