InAs/GaAsSb in-plane ultrahigh-density quantum dot lasers

InAs/InAsSb ultrahigh-density quantum dots (UHD QDs) with a density of 1×1012 cm-2 were fabricated using molecular beam epitaxy, and their photoluminescence (PL) properties were characterized. Through temperature dependences of PL energy, intensity and decay time of UHD QDs, it was found that in-plane strong coupling between adjacent QDs of excited and ground states due to homogeneous broadening of QD levels progressed above 60 K and above 100 K, respectively. The findings regarding the strong coupling at ground states were consistent with the temperature dependence of PL minimum energy outlined in Appendix. In addition, abnormal phenomenon in PL full width at half maximum (FWHM) was attributed to the in-plane miniband formation resulting from strong coupling.

Section: Introductionmentioning

confidence: 92%

Abnormal photoluminescence properties of InAs/InAsSb in-plane ultrahigh-density quantum dots

Oon,

Ohyama,

Miyashita

et al. 2024

“…[12][13][14][15][16] These UHD QDs have been applied to IBSCs and QD lasers. 14,17,18) In particular, the QD density in the InAs/ InAsSb UHD QD layer reached to 1 × 10 12 cm −2 , 15,16) and these QDs were closely packed in-plane. Therefore, in-plane electronically strong coupling is expected to occur in the InAs/ InAsSb UHD QD layer.…”

Section: Introductionmentioning

confidence: 96%

Demonstration of in-plane miniband formation in InAs/InAsSb ultrahigh-density quantum dots by analysis of temperature dependence of photoluminescence

Tatsugi

Miyashita²,

Sogabe³

et al. 2022

Self Cite

Self-assembled InAs/InAsSb ultrahigh-density quantum dots (UHD QDs) were grown on GaAs(001) substrate by molecular beam epitaxy. The QD density was 1×1012 cm-2, and an average separation distance between adjacent QD edges was less than 3 nm. The temperature dependence of photoluminescence (PL) minimum energy of UHD QDs was measured and was divided clearly into three temperature regions: (1) fitting to upper Varshni shift at 15 K to 80 K, (2) decreasing from upper Varshni shift from 80 K to 180 K and (3) re-fitting to lower Varshni shift at 180 K to 290 K. The energy difference between upper and lower Varshni curves increased with increasing QD density. This anomalous temperature dependence of PL minimum energy was demonstrated by a simulation model of miniband formation due to electronically strong coupling of adjacent QDs, including the temperature dependence of the homogeneous broadening in the QD.

“…In practical examples of lasers based on QDs technology, InSb and InAs QDs such as Ⅲ-Ⅴ semiconductors are proposed, [7][8][9][10] and it has been reported that high carrier injection efficiency with ultra-low threshold current has been achieved at RT in laser applications of InAs QDs. 8,9) Group III-V semiconductors are mostly direct-transition-type semiconductors, and they have very high potential for optical devices due to their high optical conversion efficiency. However, they are not compatible with Si-based materials for Si photonics applications since they can form interface defects and be dopants for group-Ⅳ system.…”

Section: Introductionmentioning

confidence: 99%

Strain and optical characteristics analyses of three-dimentional self-ordered multilayered SiGe nanodots by photoluminescence and Raman spectroscopy

Ito,

Yokogawa,

Wen

et al. 2024

The strain state, optical properties, and band structure of the self-ordered multilayered silicon-germanium (SiGe) nanodots, which are staggered and dot-on-dot alignment and embedded by Si spacer, were evaluated by Raman spectroscopy and low-temperature Photoluminescence (PL). These results suggest that the compressive strain applied to the staggered nanodots is smaller than that of the dot-on-dot nanodots, which contributes to the shrinking of the bandgap of the staggered nanodots. Strong PL intensity was observed from the nanodots compared to the single crystalline bulk SiGe due to the carrier confinement and high crystal quality of the nanodots. The stack-controlled nanodots showed a redshift of the PL peaks compared to the bulk SiGe and the effect of strain induced in SiGe nanodots might not be enough to explain this phenomenon. The cause of the redshift was clarified by considering the hetero band structure of the nanodots and the tensile strained spacer.