Yao Z H, Wang X, Chen H M, Wang T, Qin L, Liu J, Zhang Z Y
School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, People's Republic of China.
Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China.
Nanotechnology. 2021 Oct 29;33(3). doi: 10.1088/1361-6528/ac2f5e.
The modulation p-doping technique has emerged as an effective way to optimize the carrier dynamics process of quantum dot (QD) structures. Here, the laser structures based on the 1.3m multiple-layer InAs/GaAs QD were fabricated with and without modulation p-doping. The carrier relaxation rate was increased after modulation p-doping, as demonstrated by transient absorption spectroscopy. The higher relaxation rate in p-doped QDs could be explained by more rapid carrier-carrier scattering process originating from increasing of the hole quasi-Fermi-level movement that increases the probability of occupancy of the valence states. In addition, the lasing behavior of Fabry-Perot lasers with and without modulation p-doping was investigated and compared. It was found that the ground state (GS) lasing in the absence of facet coating was successfully achieved in a p-doped laser diode with short cavity length (400m), which can be attributed to the higher GS saturation gain caused by p-doping. With assistance of a designed TiO/SiOfacet coating whose central wavelength (∼1480 nm) is far beyond the lasing wavelength of 1310 nm, the GS lasing could be realized in a laser diode with short cavity lengths (300m) under continuous wave operation at room temperature, implying great potential for the development of low-cost and high-speed directly modulated lasers.
调制p型掺杂技术已成为优化量子点（QD）结构载流子动力学过程的有效方法。在此，制备了基于1.3μm多层InAs/GaAs量子点的有和没有调制p型掺杂的激光结构。瞬态吸收光谱表明，调制p型掺杂后载流子弛豫速率增加。p型掺杂量子点中较高的弛豫速率可以通过空穴准费米能级移动增加导致的更快的载流子-载流子散射过程来解释，这增加了价态占据概率。此外，研究并比较了有和没有调制p型掺杂的法布里-珀罗激光器的激射行为。发现在短腔长（400μm）的p型掺杂激光二极管中成功实现了无腔面涂层时的基态（GS）激射，这可归因于p型掺杂引起的更高的基态饱和增益。在中心波长（~1480nm）远超过激射波长1310nm的设计的TiO/SiO2腔面涂层的辅助下，在室温连续波工作下，短腔长（300μm）的激光二极管中可实现基态激射，这意味着低成本和高速直接调制激光器的发展具有巨大潜力。
