Jo Byounggu, Lee Hyunjung, Choi Ilgyu, Kim Jiin, Kim Jin Soo, Han Won Seok, Song Jung Ho, Oh Dae Kon, Noh Sam Kyu, Leem Jae-Young
J Nanosci Nanotechnol. 2014 Dec;14(12):9623-7. doi: 10.1166/jnn.2014.10189.
We report the influences of a dot-in-a-well structure with a thin GaAs layer and the thickness of a waveguide (WG) on the lasing characteristics of InAs quantum dots (QDs) based on InP. The QD laser diodes (QDLDs) consist of seven-stacked InAs QDs separated by a 10 nm-thick InGaAsP (1.15 μm, 1.15Q-InGaAsP) layer, which is further sandwiched by a 800 nm-thick 1.15Q-lnGaAsP WG (reference QDLD). For comparison, the InAs QDs were inserted into the InGaAsP (1.35 μm, 1.35Q-InGaAsP) quantum well embedded in the 1.15Q-InGaAsP matrix at the active layer. And a 2 monolayer (ML)-thick GaAs layer was additionally introduced right before the QD layer (GDWELL-LDs). Lasing emission from the reference QDLD with only the 1.15Q-InGaAsP structure was not observed at room temperature (RT). However, the lasing emission from the GDWELL-LDs was clearly observed at the wavelength of 1.46 μm at RT under continuous-wave (CW) mode. The threshold current density of the GDWELL-LD with the 800 nm-thick InGaAsP WG was measured to be 830 A/cm2, which was lower than that of the GDWELL-LD with the 200 nm-thick WG (900 A/cm2). Also, the slope efficiency of the GDWELL-LD was significantly improved with increasing thickness of the InGaAsP WG.
我们报道了具有薄GaAs层的阱中量子点结构以及波导（WG）厚度对基于InP的InAs量子点（QD）激光特性的影响。量子点激光二极管（QDLD）由七个堆叠的InAs量子点组成，中间隔着一个10 nm厚的InGaAsP（1.15 μm，1.15Q-InGaAsP）层，该层又被一个800 nm厚的1.15Q-InGaAsP WG夹在中间（参考QDLD）。为了进行比较，将InAs量子点插入到有源层中嵌入1.15Q-InGaAsP基质的InGaAsP（1.35 μm，1.35Q-InGaAsP）量子阱中。并且在量子点层之前额外引入了一个2单层（ML）厚的GaAs层（GDWELL-LDs）。仅具有1.15Q-InGaAsP结构的参考QDLD在室温（RT）下未观察到激光发射。然而，在连续波（CW）模式下，室温下从GDWELL-LDs中清晰地观察到了波长为1.46 μm的激光发射。测量得到具有800 nm厚InGaAsP WG的GDWELL-LD的阈值电流密度为830 A/cm²，低于具有200 nm厚WG的GDWELL-LD的阈值电流密度（900 A/cm²）。此外，随着InGaAsP WG厚度的增加，GDWELL-LD的斜率效率显著提高。
