High-temperature reliable quantum-dot lasers on Si with misfit and threading dislocation filters

Abstract

Direct epitaxial growth of III-V light sources on Si photonic chips is promising to realize low-cost and high-functionality photonic integrated circuits. Historically, high temperature reliability of such devices has been the major roadblock due to crystalline defects from heteroepitaxy. Here, by reducing the threading dislocation densities to ∼ 1 × 1 0 6 c m − 2 and efficiently removing misfit dislocations above and below the active region, 1.3 µm InAs quantum-dot lasers directly grown on industry standard on-axis Si (001) show record-breaking reliability at 80°C. The hero device shows minimum degradation after more than 1200 h of constant current stress. Statistical analysis shows an extrapolated lifetime of over 22 years for the median devices, bringing these devices one big step closer to real world applications.

Mid-infrared III–V semiconductor lasers epitaxially grown on Si substrates

“…However, these devices do not cover the MIR range below 3 µm. The threading defect density thus needs to be mitigated through optimization of the buffer layer growth and structure, as demonstrated in the near-IR 63 , to improve the DL performance. Quantum dots however are not a straightforward option since the InSb/GaSb material system intrinsically gives rise to low-radiative efficiency QDs 115 , 116 .…”

“…However, dislocation arms still thread through the whole heterostructure. Various strategies have proved efficient to reduce threading dislocation densities (TDDs) down to the 10 6 cm −2 range for InAs/GaAs QDLs grown on Si 59 – 63 . However, they have not been implemented yet in the growth of III-Sbs on Si and TDDs are typically in the 10 7 –10 8 cm −2 range after a couple of micrometers of growth.…”

A Review of the Reliability of Integrated IR Laser Diodes for Silicon Photonics

“…The improvements in epitaxial quality and the previously described mitigation strategies allowed to attain devices with very-high MTTF. In particular, if we define this latter parameter as the average time required for a sample operating at a constant 10 mW OP to increase by two times its initial threshold current, QD LDs with lifetimes in excess of 22 years under high temperature aging (T = 80 • C) have recently been demonstrated [44].…”

“…The former goal can either be achieved through the optimization of the growth procedure, of the buffer layer or through a well-engineered positioning of MD-trapping layers that prevent the formation of longitudinally extended defects in the proximity of the active region, which may happen during the heating-up and cooling-down phases of the growth process [42,43]. The introduction of misfit trapping layers, which block over 90% of the misfit dislocations which would otherwise grow along the active region [43,44], allows for a great increase in device reliability, as testified by the higher optical stability exhibited by devices featuring trapping layers within their epitaxy (Figure 9). This misfit growth appears to be the dominant failure mechanism for QD lasers grown on silicon substrates.…”

Perspectives on Advances in Quantum Dot Lasers and Integration with Si Photonic Integrated Circuits

“…Combining the low TDD GaAs virtual substrate with the asymmetric graded filter structure on (001) Si and inserting In 0.15 Al 0.85 As and In 0.15 Ga 0.85 As TLs in the n-and ptype cladding layers, respectively, the performance of the InAs QD laser has improved significantly (Gen VI). 71 Figure 8a is the schematic of the laser cross-section, where the inserted TLs are placed 180 nm away from the active region. Figure 8b is the SEM image of the as-cleaved laser facet.…”