Open Access
Add to BibSonomy
Abstract
InAs/GaAs quantum dot (QD) laser monolithically grown on silicon is one of the potential approaches to realizing silicon-based light sources. However, the mismatch between GaAs and Si generates a high density of threading dislocations (TDs) and antiphase boundaries (APBs), which trap carriers and adversely affect device performance. In this paper, we present a simple method to reduce the threading dislocation density (TDD) merely through GaAs buffer, eliminating the intricate dislocation filter layers (DFLs) as well as any intermediate buffer layers whose compositions are different from the target GaAs. An APB-free epitaxial 2.5 µm GaAs film was grown on exact Si (001) by metalorganic chemical vapor deposition (MOCVD) with a TDD of 9.4 × 106 cm−2. InAs/GaAs QDs with a density of 5.2 × 1010 cm−2 were grown on this GaAs/Si (001) virtual substrate by molecular beam epitaxy (MBE) system. The fabricated QD laser has achieved a single facet room temperature continuous-wave output power of 138 mW with a threshold current density of 397 A/cm2 and a lasing wavelength of 1306 nm. In this work, we propose a simplified method to fabricate high-power QD lasers, which is expected to promote the application of photonic integrated circuits.
© 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
1. Introduction
The explosive development of silicon-based photonics has propelled a boom in Si-based optoelectronic devices, such as photodetectors [1], splitters [2], and wavelength division multiplexing modulators [3–5]. Nowadays, the preparation of low-cost and scalable integration Si-based light sources will greatly promote the development of Si photonic integrated circuits [6,7]. However, the natural indirect band gap of silicon brings great difficulties to the realization of an efficient silicon-based light source [8]. These research fields have aroused great interest among researchers to find new ways to realize high-performance lasers such as the III-V quantum dot (QD) lasers grown on Si-based GaAs or InP pseudosubstrate [9–13]. Generally speaking, the quality of the pseudosubstrate directly determines the performance of the Si-based QD light source.
The difference in crystal polarity between silicon and III-V semiconductors leads to the generation of antiphase boundaries (APBs). Simultaneously, the lattice mismatch between GaAs (or InP) and Si substrate will introduce a large number of threading dislocations (TDs) [14,15]. These defects act as nonradiative recombination centers and current leakage paths, seriously degrading the electro-optical conversion characteristics of the devices [16]. Therefore, to obtain high-quality epitaxial layers, reducing APBs and TDs are the primary problems faced by researchers.
As can be seen from Table 1, various buffer structures have been applied to avoid the formation of APB and to reduce the TDs. The most common method to reduce the APB is the usage of an off-cut or patterned Si substrate which benefits from the formation of double- atoms step on the Si (001) surface. However, the off-cut Si substrate is not compatible with the traditional complementary metal-oxide-semiconductor (CMOS) circuits and the pre-patterning process is difficult to achieve perfectly clean Si (111) facets [14]. Different intermediate buffer layers such as GaP, AlAs, and Ge were introduced to solve the problems, but they can only solve the problem of lattice mismatch or polarity mismatch alone. Furthermore, the growth and annealing temperature of some intermedia buffer is relatively high which also introduces difficulties in high-quality pseudosubstrate preparation. After the elimination of APBs, strained layer superlattices (SLSs) and other kinds of dislocation filter layers (DFLs) are used to reduce the TDs. These methods are serviceable but often too complicated.
Table 1. Buffer layer and related performance parameters used in various QD lasers
In 2018, John E. Bowers’ research group epitaxially deposited ∼3 µm buffer layers on APB-free GaP/Si templates to reduce the dislocation density to 7 × 106 cm−2 [17], and they further reduced the dislocation density to 1.5 × 106 cm−2 by epitaxy a ∼2.5 µm asymmetric graded filter as the DFLs [18], which is one of the most remarkable results. In 2020, Liu et al. grew DFLs, which were composed of four periods of a five-layer 10 nm In0.15Ga0.85As/10 nm GaAs and 300 nm GaAs spacing layer on Si (001) to reduce the TDD to 5 × 107 cm−2 [19]. In the same year, Yang et al. obtained a GaAs buffer layer with TDD of 4 × 106 cm−2 on Ge/Si substrate by using In0.18Ga0.82As/GaAs DFLs [20]. To explicitly compare different techniques, we summarized some recent research results about QD lasers grown on Si through GaAs pseudosubstrate and listed them in Table 1.
As far as we know, 1.5 × 106 cm−2 is the lowest TDD in GaAs/Si material system. Nevertheless, it is sufficient to fabricate high-performance QD lasers. The highest output power of 185 mW [21] and 175 mW [22] with and without facet coating are both demonstrated by John E. Bower’s group from UCSB on GaP/Si templates. Results from other research groups are also listed in Table 1.
In this paper, we reduced the TDD to 9.4 × 106 cm−2 with only 2.5 µm GaAs buffer on the exact Si (001) substrate. The QD laser grown on this GaAs pseudosubstrate obtained a room temperature continuous-wave output power of 138 mW without facet coating and a threshold current density of 397 A/cm2.
2. Experimental procedure
2.1 Crystal growth
AXITRON AIX-200 metalorganic chemical vapor deposition (MOCVD) system and DCA Instruments-P600 molecular beam epitaxy (MBE) system were used to prepare epitaxial structures of GaAs buffer layer and QDs structures respectively. Unintentionally selected silicon substrate is cleaned by H2SO4 modified Radio Corporation of America (RCA) cleaning process to remove organic pollutants, particles, metal contaminants, and natural oxide film on the surface of the silicon wafer. Further effective surface treatment in H2 and AsH3 atmosphere at 735 °C for 20 min was applied to promote atomic reconfiguration of the Si (001) surface [23,15], which is a crucial step to obtaining an APB-free GaAs epilayer. After the preprocessing, 2.5 µm GaAs buffer was grown by a modified three-step method under a chamber pressure of 100 mbar. A 20 nm low temperature (LT 420 °C) layer was grown, followed by a ∼300 nm intermediate temperature (IT 630 °C) layer and a ∼2.2 µm high temperature (HT 700 °C) layer. The LT layer is a critical growth step to suppress APBs and reduce the TDD [24]. To promote dislocation annihilation [25,26], two periods of thermal cycle annealing were carried out, each of which includes three cycles of 720 °C and 450 °C alternations.
After MOCVD growth, the GaAs/Si template was transferred into the MBE reaction chamber for InAs QD growth. Based on the original GaAs buffer, an 800 nm highly doped n-contact layer was grown. Six layers of InAs/GaAs QD active region was sandwiched between two 1.5 µm Al0.4Ga0.6As cladding layer. Finally, 200 nm p-type GaAs were grown on the top of the structure as a p-contact layer. The complete epitaxial structure is shown in Fig. 1.
2.2 Device fabrication
The as-grown material was then fabricated into broad-area lasers with varying stripe widths using standard photolithography and dry etching techniques. Mesas of different widths were etched into the surface of the active region to form ridge waveguides for better confinement of light and carriers. After opening the metal contact window on the 300 nm SiO2 electrical isolation layer, Ti/Pt/Au and AuGe/Ni/Au were deposited to form P and N metal electrodes, respectively. Subsequently, it was annealed at 480 °C for 190 s to improve the ohmic contact performance. The silicon substrate was thinned to ∼100 µm and the laser facets were formed by cleaving without any facet coating. Schematic and scanning electron microscopy (SEM) images of the cleaved cross-sectional facet of a fabricated InAs/GaAs QD laser on a silicon substrate are shown in Fig. 2. As shown in Fig. 2(b), the cavity surface is extremely clean and flat, which is accessible to achieve low mirror loss lasers. The chip was mounted on a copper heatsink and pumped under a continuous wave.
Fig. 2. (a) Schematic diagram of the laser cross-section. (b) SEM image of the cross-section of an as-cleaved laser.
2.3 Measurements
SEM was used to observe the elimination of the APB and the laser cavity surface formed after cleaving. Then, the TDD in the GaAs/Si template was calculated and measured by X-ray diffractometer (XRD) and electron channeling contrast imaging (ECCI). Transmission electron microscope (TEM) was used for the further characterization of defects confined within the GaAs buffer layer. The optical properties of the whole structure were measured by photoluminescence (PL), and the morphology of the QDs was measured by atomic force microscopy (AFM). Finally, the electro-optic properties of the device were characterized by the spectrometer.
3. Results and discussion
3.1 Buffer layer and InAs/GaAs QD structure on GaAs/Si (001)
We used various measurement methods to evaluate the quality of the GaAs buffer layer grown by MOCVD. The surface morphology of the GaAs buffer was characterized by an AFM system. The measured AFM image indicates that a small RMS surface roughness of 2.85 nm has been achieved within the scanning area of 10 × 10 µm2 as shown in Fig. 3(a). As shown in Fig. 3(b), the characterization results of XRD show the perfect epitaxial crystal quality, in which the peaks of GaAs and Si are located at 33.07° and 34.56° respectively. The FWHM of GaAs is 147.6 arcsec. Substituting the FWHM into Eq. (1) yields a TDD of 9.2 × 106 cm−2 [27].
where ${D_{TD}}$ is the penetration dislocation density of GaAs epitaxial layer, β represents the FWHM of the GaAs epitaxial layer, b is the length of the Boggs vector, $b = \frac{a}{2}\sqrt {{h^2} + {k^2} + {l^2}} $, (h k l) is the measured crystal direction of the epitaxial layer material for GaAs (004), a represents the lattice constant.Fig. 3. (a) AFM image of the GaAs buffer surface, the RMS is 2.85 nm within a scanning area of 10 × 10 µm2. (b) XRD of the 2.5 µm GaAs buffer layer grown on Si (001). The radiation source is Cu target radiation with a wavelength of 1.5405 Å. (c) ECCI diagram of GaAs buffer interface, showing that TDD is as low as 9.4 × 106 cm−2. (d) Cross-sectional TEM view of the as-grown laser material of GaAs/Si. (e) and (f) are SEM images of the GaAs buffer interface. The APB before the optimization is clearly visible in (e), and the perfect GaAs buffer interface without any APB after optimization is shown in (f).
Electron channeling contrast imaging was then used to further assess the TDD, as shown in Fig. 3(c). The average TDD was found to be 9.4 × 106 cm−2 by surveying an area of ∼127 µm2. It is consistent with the TDD of 9.2 × 106 cm−2 calculated by Eq. (1). Demonstrating that TDDs in the GaAs buffer layers are effectively reduced by a three-step method combined with rapid cycle annealing [28].
Figure 3(d) shows a cross-sectional bright-field TEM image of the GaAs/Si interface. Defects are generated at the interface of GaAs/Si and extend to the GaAs buffer layer. As the GaAs buffer thickness increased, the TDD was significantly reduced. Combined with multiple cycles of thermal annealing, the defects are suppressed within GaAs buffer layer thickness of less than 1.5 µm. APBs are clearly shown in Fig. 3(e), which was obtained before optimization. After the effective treatment on the Si substrate surface, the APBs were fully eliminated through surface annealing and growth condition optimization as illustrated in the SEM image in Fig. 3(f). The pretreatment under H2 and AsH3 atmosphere is the crucial step, which can promote the formation of double-atom steps on silicon surface [23,29].
Figure 4 shows the room temperature photoluminescence (PL) spectrum of the InAs QDs, which has a peak intensity of around 1296 nm for the ground-state transition and a full width at half maximum of about 34 meV. The inset of Fig. 4 is the AFM image of the as-grown dots, showing that the areal density of the dots is about 5.2 × 1010 cm−2.
Fig. 4. Photoluminescence spectrum of the as-grown sample. Inset: AFM image of QD with a density of 5.2 × 1010 cm−2. The image has a size of 1 × 1 µm2.
In conclusion, we achieved high-quality epitaxial layers only by growing a 2.5 µm GaAs buffer layer. This simple structure avoids the injection of current through the SLSs interface and the cross-hatching introduced by the SLSs [22]. Moreover, the whole process can be further simplified, which is expected to promote the application of photonic integrated circuits.
3.2 Device properties
Figure 5 shows the light-current-voltage (L-I-V) characteristics of the broad-area laser with a 2 mm cavity length and 50 µm ridge width at room temperature. A clear knee behavior in the light-current (L-I) curve is observed at the lasing threshold current of 397 mA, which corresponds to a threshold current density (Jth) of 397 A/cm2 or 66.2 A/cm2 per QD layer. Moreover, as the device has GaAs-only growth and has a buffer as thin as ∼2.5 µm, the compatibility of the device with the industry-standard fabrication process has also improved. Furthermore, for the L-I curve, a single facet output power of 138 mW is obtained at an injection current of 2 A, and the slope efficiency is 0.085 W/A. We note that the L-I curve exhibits many kinks as the injection current increases. It is hereby emphasized that these kinks observed in the L-I curve mainly come from the redistribution of current carriers from different modes within the ground state and mode competition [30].
Fig. 5. Typical L-I-V characteristics of an as-cleaved laser with a cavity length of 2 mm and a ridge width of 50 µm. Inset: the emission spectrum of the InAs/GaAs QD laser on GaAs/Si (001) substrate at room temperature.
The emission spectra for the InAs/GaAs QD laser on GaAs/Si (001) is shown in Fig. 6. A spontaneous emission spectrum with a broad FWHM of 27 nm is observed at a peak wavelength of ∼1302 nm at a driven current of 300 mA. With the increase of injection current, the peak intensity increases significantly, the lasing wavelength has a slight red shift and multimode lasing has been observed. As the injection current increases to 600 mA, the peak narrows to 2.7 nm, and the intensity sharply increases. The typical mode competition behavior of broad-area lasers exists when the injection current increases from 420 mA to 600 mA.
Fig. 6. Lasing spectra of a device with 2000 × 50 µm2 cavity at various injection currents at room temperature.
The operating temperature is one of the important indexes to evaluate the performance of lasers. Figure 7 shows the temperature dependence of the L-I characteristics under CW conditions. This Si-based QD laser has a maximum heatsink temperature of 65 °C for lasing operation, still producing an output power of 3.6 mW as shown in the bottom right of the figure.
Fig. 7. (a) High-temperature measurements of a device with a 2000 × 50 µm2 cavity, showing lasing up to 65 °C under CW operation. (b) Natural logarithm of threshold current versus temperature. (c) An enlarged view of the current versus output power curve at 65 °C.
We also calculated the characteristic temperature by using an exponential function of Ith ${\propto} $ exp(T/T0). The natural logarithm of the threshold current versus stage temperature is given in Fig. 7(b). The characteristic temperature T0 is 37 K in the range of 15-65 °C. The p-type modulation doping technique can further increase the characteristic temperature of the device [31], but also needs to consider its adverse effect on the threshold current of the device [32].
4. Conclusion
In conclusion, we successfully demonstrated the broad-area high-power InAs/GaAs quantum-dot lasers grown on on-axis Si (001) without using any DFLs and intermediate buffer layers. Surface pretreatment for the Si substrate and multiple annealing cycles for GaAs were combined to achieve the APB-free and low-TDD GaAs film. The device exhibits a CW lasing at ∼1.3 µm with a threshold current density of 397 A/cm2 and a single facet output power of 138 mW at room temperature. Compared with other monolithic hetero-epitaxy schemes on Si (001), we provide an innovative way to prepare low-cost, CMOS-compatible silicon-based light sources, which is conducive to promoting the commercial development of silicon photonic interconnects.
Funding
National Key Research and Development Program of China (2018YFE0203101, 2018YFB2200104); National Natural Science Foundation of China (62004190); Fundamental Research Funds for the Central Universities (BUPT, 2022RC05).
Acknowledgments
The authors would like to thank the anonymous reviewers for their valuable comments that helped improve this paper.
Disclosures
The authors declare no conflicts of interest.
Data availability
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
References
1. B. W. Jia, K. H. Tan, W. K. Loke, S. Wicaksono, K. H. Lee, and S. F. Yoon, “Monolithic Integration of InSb Photodetector on Silicon for Mid-Infrared Silicon Photonics,” ACS Photonics 5(4), 1512–1520 (2018). [CrossRef]
2. H. Wu, Y. Tan, and D. Dai, “Ultra-broadband high-performance polarizing beam splitter on silicon,” Opt. Express 25(6), 6069–6075 (2017). [CrossRef]
3. J. Wang and L. R. Chen, “Low crosstalk Bragg grating/Mach-Zehnder interferometer optical add-drop multiplexer in silicon photonics,” Opt. Express 23(20), 26450–26459 (2015). [CrossRef]
4. L. Ansheng, L. Ling, Y. Chetrit, J. Basak, H. Nguyen, D. Rubin, and M. Paniccia, “Wavelength Division Multiplexing Based Photonic Integrated Circuits on Silicon-on-Insulator Platform,” IEEE J. Sel. Top. Quantum Electron. 16(1), 23–32 (2010). [CrossRef]
5. P. Dong, “Silicon Photonic Integrated Circuits for Wavelength-Division Multiplexing Applications,” IEEE J. Sel. Top. Quantum Electron. 22(6), 370–378 (2016). [CrossRef]
6. J. C. Norman, D. Jung, Y. Wan, and J. E. Bowers, “Perspective: The future of quantum dot photonic integrated circuits,” APL Photonics 3(3), 030901 (2018). [CrossRef]
7. C. Shang, Y. Wan, J. Selvidge, E. Hughes, R. Herrick, K. Mukherjee, J. Duan, F. Grillot, W. W. Chow, and J. E. Bowers, “Perspectives on Advances in Quantum Dot Lasers and Integration with Si Photonic Integrated Circuits,” ACS Photonics 8(9), 2555–2566 (2021). [CrossRef]
8. D. Liang and J. E. Bowers, “Recent progress in lasers on silicon,” Nat. Photonics 4(8), 511–517 (2010). [CrossRef]
9. Y. Wan, J. Norman, Q. Li, M. J. Kennedy, D. Liang, C. Zhang, D. Huang, Z. Zhang, A. Y. Liu, A. Torres, D. Jung, A. C. Gossard, E. L. Hu, K. M. Lau, and J. E. Bowers, “1.3 µm submilliamp threshold quantum dot micro-lasers on Si,” Optica 4(8), 940–944 (2017). [CrossRef]
10. Y. Wan, S. Zhang, J. C. Norman, M. J. Kennedy, W. He, S. Liu, C. Xiang, C. Shang, J.-J. He, A. C. Gossard, and J. E. Bowers, “Tunable quantum dot lasers grown directly on silicon,” Optica 6(11), 1394 (2019). [CrossRef]
11. T. Zhou, M. Tang, G. Xiang, B. Xiang, S. Hark, M. Martin, T. Baron, S. Pan, J. S. Park, Z. Liu, S. Chen, Z. Zhang, and H. Liu, “Continuous-wave quantum dot photonic crystal lasers grown on on-axis Si (001),” Nat. Commun. 11(1), 977 (2020). [CrossRef]
12. Y. Wan, C. Xiang, J. Guo, R. Koscica, M. J. Kennedy, J. Selvidge, Z. Zhang, L. Chang, W. Xie, D. Huang, A. C. Gossard, and J. E. Bowers, “High Speed Evanescent Quantum-Dot Lasers on Si,” Laser Photonics Rev. 15, 2100057 (2021). [CrossRef]
13. Y. Wang, S. Chen, Y. Yu, L. Zhou, L. Liu, C. Yang, M. Liao, M. Tang, Z. Liu, J. Wu, W. Li, I. Ross, A. J. Seeds, H. Liu, and S. Yu, “Monolithic quantum-dot distributed feedback laser array on silicon,” Optica 5(5), 528–533 (2018). [CrossRef]
14. B. Kunert, Y. Mols, M. Baryshniskova, N. Waldron, A. Schulze, and R. Langer, “How to control defect formation in monolithic III/V hetero-epitaxy on (100) Si? A critical review on current approaches,” Semicond. Sci. Technol. 33(9), 093002 (2018). [CrossRef]
15. Q. Li and K. M. Lau, “Epitaxial growth of highly mismatched III-V materials on (001) silicon for electronics and optoelectronics,” Prog. Cryst. Growth Charact. Mater. 63(4), 105–120 (2017). [CrossRef]
16. A. Y. Liu, S. Srinivasan, J. Norman, A. C. Gossard, and J. E. Bowers, “Quantum dot lasers for silicon photonics [Invited],” Photonics Res. 3(5), B1–B9 (2015). [CrossRef]
17. K. S. Deacon, Y. Shih, R. E. Meyers, R. Herrick, A. Torres, M. J. Kennedy, Y. Wan, Z. Zhang, J. E. Bowers, A. C. Gossard, D. Jung, and J. Norman, “High performance quantum dot lasers epitaxially integrated on Si,” in Quantum Communications and Quantum Imaging XVI, (2018).
18. C. Shang, E. Hughes, Y. Wan, M. Dumont, R. Koscica, J. Selvidge, R. Herrick, A. C. Gossard, K. Mukherjee, and J. E. Bowers, “High-temperature reliable quantum-dot lasers on Si with misfit and threading dislocation filters,” Optica 8(5), 749–754 (2021). [CrossRef]
19. Z. Liu, M. Martin, T. Baron, S. Chen, A. Seeds, R. Penty, I. White, H. Liu, C. Hantschmann, M. Tang, Y. Lu, J.-S. Park, M. Liao, S. Pan, A. Sanchez, and R. Beanland, “Origin of Defect Tolerance in InAs/GaAs Quantum Dot Lasers Grown on Silicon,” J. Lightwave Technol. 38(2), 240–248 (2020). [CrossRef]
20. J. Yang, Z. Liu, P. Jurczak, M. Tang, K. Li, S. Pan, A. Sanchez, R. Beanland, J.-C. Zhang, H. Wang, F. Liu, Z. Li, S. Shutts, P. Smowton, S. Chen, A. Seeds, and H. Liu, “All-MBE grown InAs/GaAs quantum dot lasers with thin Ge buffer layer on Si substrates,” J. Phys. D: Appl. Phys. 54(3), 035103 (2021). [CrossRef]
21. D. Jung, Z. Zhang, J. Norman, R. Herrick, M. J. Kennedy, P. Patel, K. Turnlund, C. Jan, Y. Wan, A. C. Gossard, and J. E. Bowers, “Highly Reliable Low-Threshold InAs Quantum Dot Lasers on On-Axis (001) Si with 87% Injection Efficiency,” ACS Photonics 5(3), 1094–1100 (2018). [CrossRef]
22. D. Jung, J. Norman, M. J. Kennedy, C. Shang, B. Shin, Y. Wan, A. C. Gossard, and J. E. Bowers, “High efficiency low threshold current 1.3 µm InAs quantum dot lasers on on-axis (001) GaP/Si,” Appl. Phys. Lett. 111(12), 122107 (2017). [CrossRef]
23. M. Martin, D. Caliste, R. Cipro, R. Alcotte, J. Moeyaert, S. David, F. Bassani, T. Cerba, Y. Bogumilowicz, E. Sanchez, Z. Ye, X. Y. Bao, J. B. Pin, T. Baron, and P. Pochet, “Toward the III–V/Si co-integration by controlling the biatomic steps on hydrogenated Si (001),” Appl. Phys. Lett. 109(25), 253103 (2016). [CrossRef]
24. D. Choi, J. S. Harris, E. Kim, P. C. McIntyre, J. Cagnon, and S. Stemmer, “High-quality III–V semiconductor MBE growth on Ge/Si virtual substrates for metal-oxide-semiconductor device fabrication,” J. Cryst. Growth 311(7), 1962–1971 (2009). [CrossRef]
25. M. Yamaguchi, T. Nishioka, and M. Sugo, “Analysis of strained-layer superlattice effects on dislocation density reduction in GaAs on Si substrates,” Appl. Phys. Lett. 54(1), 24–26 (1989). [CrossRef]
26. J. W. Lee, H. Shichijo, H. L. Tsai, and R. J. Matyi, “Defect reduction by thermal annealing of GaAs layers grown by molecular beam epitaxy on Si substrates,” Appl. Phys. Lett. 50(1), 31–33 (1987). [CrossRef]
27. J. E. Ayers, “The measurement of threading dislocation densities in semiconductor crystals by X-ray diffraction,” J. Cryst. Growth 135(1-2), 71–77 (1994). [CrossRef]
28. W. Chen, J. Wang, L. Zhu, G. Wu, Y. Yang, C. Xiao, J. Li, H. Wang, Y. Jia, Y. Huang, and X. Ren, “Theoretical and experimental study on epitaxial growth of antiphase boundary free GaAs on hydrogenated on-axis Si (001) surfaces,” J. Phys. D: Appl. Phys. 54(44), 445102 (2021). [CrossRef]
29. R. Alcotte, M. Martin, J. Moeyaert, R. Cipro, S. David, F. Bassani, F. Ducroquet, Y. Bogumilowicz, E. Sanchez, Z. Ye, X. Y. Bao, J. B. Pin, and T. Baron, “Epitaxial growth of antiphase boundary free GaAs layer on 300 mm Si(001) substrate by metalorganic chemical vapour deposition with high mobility,” APL Mater. 4(4), 046101 (2016). [CrossRef]
30. T. V. Torchynska, R. C. Tamayo, G. Polupan, I. J. G. Moreno, and A. E. Echavarria, “Annealing Impact on Emission of InAs Quantum Dots in GaAs/Al0.30Ga0.70As Structures with Different Capping Layers,” J. Electron. Mater. 50(8), 4633–4641 (2021). [CrossRef]
31. H. Y. Liu, S. L. Liew, T. Badcock, D. J. Mowbray, M. S. Skolnick, S. K. Ray, T. L. Choi, K. M. Groom, B. Stevens, F. Hasbullah, C. Y. Jin, M. Hopkinson, and R. A. Hogg, “p-doped 1.3µm InAs∕GaAs quantum-dot laser with a low threshold current density and high differential efficiency,” Appl. Phys. Lett. 89(7), 073113 (2006). [CrossRef]
32. J. C. Norman, D. Jung, Z. Zhang, Y. Wan, S. Liu, C. Shang, R. W. Herrick, W. W. Chow, A. C. Gossard, and J. E. Bowers, “A Review of High-Performance Quantum Dot Lasers on Silicon,” IEEE J. Quantum Electron. 55(2), 1–11 (2019). [CrossRef]
33. T. Tianyi, “Investigation into the InAs/GaAs quantum dot material epitaxially grown on silicon for O band lasers,” J. Semicond. 43(1), 012301 (2022). [CrossRef]
34. Y. Wan, C. Shang, J. Norman, B. Shi, Q. Li, N. Collins, M. Dumont, K. M. Lau, A. C. Gossard, and J. E. Bowers, “Low Threshold Quantum Dot Lasers Directly Grown on Unpatterned Quasi-Nominal (001) Si,” IEEE J. Sel. Top. Quantum Electron. 26(2), 1–9 (2020). [CrossRef]
35. Y. Wan, J. C. Norman, Y. Tong, M. J. Kennedy, W. He, J. Selvidge, C. Shang, M. Dumont, A. Malik, H. K. Tsang, A. C. Gossard, and J. E. Bowers, “1.3 µm Quantum Dot-Distributed Feedback Lasers Directly Grown on (001) Si,” Laser Photonics Rev. 14, 2000037 (2020). [CrossRef]
36. L. Wang, B. Shi, H. Zhao, S. S. Brunelli, B. Song, D. C. Oakley, and J. Klamkin, “Toward All MOCVD Grown InAs/GaAs Quantum Dot Laser on CMOS-compatible (001) Silicon,” in Conference on Lasers and Electro-Optics (2019), 1–2.
37. C. Shang, A. C. Gossard, J. E. Bowers, Y. Wan, J. C. Norman, N. Collins, I. MacFarlane, M. Dumont, S. Liu, Q. Li, and K. M. Lau, “Low-Threshold Epitaxially Grown 1.3-µm InAs Quantum Dot Lasers on Patterned (001) Si,” IEEE J. Sel. Top. Quantum Electron. 25(6), 1–7 (2019). [CrossRef]
38. K. Li, Z. Liu, M. Tang, M. Liao, D. Kim, H. Deng, A. M. Sanchez, R. Beanland, M. Martin, T. Baron, S. Chen, J. Wu, A. Seeds, and H. Liu, “O-band InAs/GaAs quantum dot laser monolithically integrated on exact (0 0 1) Si substrate,” J. Cryst. Growth 511, 56–60 (2019). [CrossRef]
39. D. Jung, J. Norman, Y. Wan, S. Liu, R. Herrick, J. Selvidge, K. Mukherjee, A. C. Gossard, and J. E. Bowers, “Recent Advances in InAs Quantum Dot Lasers Grown on On-Axis (001) Silicon by Molecular Beam Epitaxy,” Phys. Status Solidi A 216(1), 1800602 (2019). [CrossRef]
40. J. Kwoen, B. Jang, J. Lee, T. Kageyama, K. Watanabe, and Y. Arakawa, “All MBE grown InAs/GaAs quantum dot lasers on on-axis Si (001),” Opt. Express 26(9), 11568–11576 (2018). [CrossRef]
41. S. Chen, M. Liao, M. Tang, J. Wu, M. Martin, T. Baron, A. Seeds, and H. Liu, “Electrically pumped continuous-wave 1.3 microm InAs/GaAs quantum dot lasers monolithically grown on on-axis Si (001) substrates,” Opt. Express 25(5), 4632–4639 (2017). [CrossRef]
