Abstract
III–V semiconductors monolithically grown on Si substrates are expected to be an ideal solution to integrate highly efficient light-emitting devices on a Si platform. However, the lattice mismatch between III–V and Si generates a high density of threading dislocations (TDs) at the interface between III–V and Si. Some of these TD will propagate into the III–V active region and lead to device degradation. By introducing defect filter layers (DFLs), the density of TDs propagating into the III–V layers can be significantly reduced. In this paper, we present an investigation on the development of InGaAs/GaAs strained-layer superlattices as DFLs for 1.3-μm InAs/GaAs quantum-dot lasers monolithically grown on a Si substrate. We compare two broad-area InAs/GaAs quantum-dot lasers with non-optimized and optimized InGaAs/GaAs DFLs. The laser device with optimal DFLs has a lower room-temperature threshold current density of 99 A/cm2 and higher maximum operation temperature of 88 °C, compared with 174 A/cm2 and 68 °C for the reference laser.
Highlights
In order to achieve fast chip-to-chip and system-to-system optical communication with Si photonic integrated circuits, Si-based efficient and reliable light emitting sources are required
In conclusion, we have investigated the optimization of InGaAs/GaAs strained-layer superlattices (SLSs) defect filter layers (DFLs) by modifying (i) the GaAs spacer layer growth conditions, and (ii) the indium composition and GaAs thickness in InGaAs/GaAs SLSs
The work confirms that the design and growth of DFLs play a critical role in the success of quantum dot (QD) lasers monolithically grown on Si
Summary
In order to achieve fast chip-to-chip and system-to-system optical communication with Si photonic integrated circuits, Si-based efficient and reliable light emitting sources are required. A combination of high efficacy DFLs and III-V QDs has been considered to be the most attractive approach for achieving III–V/Si lasers. Wang et al reported the first 1.3-μm InAs/GaAs QD lasers monolithically grown on Si substrates [23], while S. Continuous–wave operation of InAs/GaAs QD lasers monolithically grown on Ge/Si substrates have been reported recently [26,27,28,29]. The optimizations of the DFLs by adjusting growth conditions and structures of InGaAs/GaAs SLSs. The optimization involves in-situ thermal annealing, variation of indium composition in the SLSs, and variation of GaAs thickness in the SLSs. the performance of two InAs/GaAs QD lasers monolithically grown on Si substrates under non-optimized and optimized conditions was compared. The QD density is around 3.8 × 1010 cm-2 as presented in figure 3
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