Nanophotonic route to control electron behaviors in 2D materials.

Two-dimensional (2D) Dirac materials, e.g., graphene and transition metal dichalcogenides (TMDs), are one-atom-thick monolayers whose electronic behaviors are described by the Dirac equation.

Optimum Design of InGaN Blue Laser Diodes with Indium-Tin-Oxide and Dielectric Cladding Layers.

The efficiency of current GaN-based blue laser diodes (LDs) is limited by the high resistance of a thick p-AlGaN cladding layer. To reduce the operation voltage of InGaN blue LDs, we investigated optimum LD structures with an indium tin oxide (ITO) partial cladding layer using numerical simulations of LD device characteristics such as laser power, forward voltage, and wall-plug efficiency (WPE). The wall-plug efficiency of the optimized structure with the ITO layer was found to increase by more than 20% relative to the WPE of conventional LD structures.

Temperature Dependence of Electron Leakage Current in InGaN Blue Light-Emitting Diode Structures.

We investigated the temperature dependence of the electron leakage current in the AlGaN electron-blocking layer (EBL) of an InGaN/GaN blue light-emitting diode (LED) structure at temperatures between 20 and 100 °C. The percentage of electron leakage current was experimentally determined by fitting the measured external quantum efficiency of an LED using the recombination model. The electron leakage current decreased significantly as the temperature increased from 20 to 100 °C.

Temperature dependence of the Auger recombination coefficient in InGaN/GaN multiple-quantum-well light-emitting diodes.

This study investigated the temperature dependence of the Auger recombination coefficient (C) in an InGaN/GaN blue multiple-quantum-well (MQW) light-emitting diode structure at temperatures between 20 and 100°C. The temperature dependence of C was determined by fitting the measured external quantum efficiency (EQE) data using an analytical model or numerical simulation. In the analytical model, the carrier density in InGaN MQWs was assumed to be constant and independent of temperature.

Low-threshold optically pumped lasing in highly strained germanium nanowires.

The integration of efficient, miniaturized group IV lasers into CMOS architecture holds the key to the realization of fully functional photonic-integrated circuits. Despite several years of progress, however, all group IV lasers reported to date exhibit impractically high thresholds owing to their unfavourable bandstructures. Highly strained germanium with its fundamentally altered bandstructure has emerged as a potential low-threshold gain medium, but there has yet to be a successful demonstration of lasing from this seemingly promising material system.