Ultrafast Carrier Dynamics in p-doped InGaAs Quantum Dot Amplifiers

摘要

Semiconductor quantum dot (QD) lasers and amplifiers are considered very promising devices for optoelectronics due to a number of predicted superior performances for zero-dimensional systems. Self-assembled epitaxially grown InGaAs QDs are among the most widely investigated system in literature for optoelectronics applications. These QDs can have strong confinement energies and defect free interfaces as well as room temperature emission in the 1.3-1.55μm wavelength range, appealing for optical communication technology. Recently, InGaAs QD lasers incorporating p-type modulation doping have generated much interest due to reports of temperature insensitive threshold current, increased peak modal gain and modulation bandwidth [1,2]. p-doping provides an excess hole concentration which is thought to improve the hole density in the QD ground-state at room temperature. Additionally, it might be speculated that the increased hole density in p-doped QDs accelerates gain recovery dynamics via fast carrier-carrier scattering, as suggested by time-resolved photoluminescence experiments [3]. However no direct measurements of gain recovery dynamics in electrically-pumped p-doped InGaAs QDs have been reported so far.