chanelink logo
CHANELINK
English

Medium-long wavelength infrared quantum cascade laser of MOCVD on silicon

105
2023-08-04 16:26:34
See translation
Us researchers report 8.1 μm wavelength quantum cascade laser (QCL) grown on silicon (Si) by MOCVD [S. Xu et al., Applications. Physics Letters, v123, p031110, 2023]. "There are no previous reports of QCL growth on silicon substrates by metal-organic chemical vapor deposition (MOCVD)," commented the team from the University of Wisconsin-Madison, the University of Illinois at Urbana-Champaign and MicroLink Devices Inc.
 
This integration on silicon could lead to the development of chip scale, reliable and mass-producible photonic integrated circuits (PIC). The researchers contrast this with other integration methods such as wafer bonding: "Hybrid integration methods rely on precise alignment to achieve efficient waveguide to laser optical coupling, which in turn requires tight fabrication machining tolerances. Direct integration onto silicon through heteroepitaxy enables mid-infrared (IR) optoelectronic devices to be integrated with mature CMOS-compatible silicon platforms at low cost and high throughput."
 
Mid-infrared QCL is usually grown on indium phosphide (InP). The team paid particular attention to creating a virtual InP substrate on silicon by combining molecular beam epitaxy (MBE) and MOCVD. MOCVD is superior to MBE in production. "The remaining technical challenge is to overcome the defects and epitaxial growing-related problems caused by large lattice constant and thermal expansion mismatches (e.g., about 8% lattice mismatches) and about 50% thermal expansion coefficient mismatches between InP and primary substrates such as silicon," the researchers comment.
The arsenide portion of the template structure (Figure 1) is a limited company grown on a commercial (001) GaP/Si template (supplied by NAsP III/V) using a solid source MBE. The substrate is nominally coaxial and compatible with high-throughput industrial-scale CMOS electronics production. The initial layer consists of an Indium Gallium Arsenide (InGaAs) dislocation filter layer (DFL) sandwiched in GaAs. By keeping the thickness of the initial arsenide layer at 0.5 μm, the researchers sacrificed some of the potential for reducing the penetration dislocation density (TDD). The GaAs layer grows in two steps, first at low temperatures of 500°C and then at higher temperatures (580/610°C for the lower/upper layers, respectively). As far as the upper layers are concerned, one motivation for doing so is to avoid the escape of indium in InGaAs DFL.
 
The upper InP metaseptic buffer (MBL) portion of the template grows through MOCVD and includes four additional DFLS, consisting of three 2nm/37nm InAs/InP pairs.
 
The QCL is completed using MOCVD and has a total epitaxial thickness (including the metamorphic buffer layer and the laser layer) of approximately 13 μm. QCL/Si did not show cracks, which the team believes could be due to two factors: the small sample size of 1.7cmx1.7cm, and the curvature accumulation mitigated by the 800 μm thick silicon substrate. The TDD for the arsenide portion of the template was estimated to be 1.0 x109 / cm-2. InP MBL reduces this to 7.9x108 /cm 2.
Under pulsed operation, the threshold current density on silicon is 22% lower than that of devices grown on bulk InP substrates during the same process run: in the figure, 1.50kA/cm 2 and 1.92kA /cm 2, respectively. The researchers comment: "This may reflect reduced incorporation of silicon dopants within the active nuclear superlattices due to pre-existing defects or differences in the growth temperatures of the silicon and InP substrate surfaces. In addition, uneven growth around the defect site may reduce carrier mobility and tunneling efficiency, which would explain the higher series resistance observed in devices grown on silicon."
 
The higher the voltage required to provide a given current injection in a silicon-based QCL, the higher the series resistance. Despite the higher series resistance, silicon-based QCL also provides higher peak optical output power: 1.64W for silicon-based devices and 1.47W for INP-based devices. The corresponding slope efficiency is 0.72W/A and 0.65W/A, and the electro-optical conversion efficiency is 2.85% and 2.50%, respectively.
 
The emission spectral analysis showed a variety of modes in the wavelength range 7.6-8.3 μm. The maximum peak values of InP and Si based devices are about 8.1 μm and 8.0 μm, respectively. These wavelengths are slightly shorter than the design target of 8.2 μm. The researchers believe that this difference may be due to local growth changes affecting layer thickness, as shown in X-ray diffraction analysis.
 
Source: Laser Network
Related Recommendations

  • German Jenoptik receives over 17 million euros in automation business orders

    Recently, Jenoptik, a leading German company in the field of optoelectronics, announced that the group successfully won multiple automation solution orders worth over 17 million euros in the second quarter of 2024.It is revealed that these orders originated from a first tier OEM supplier (unnamed) and were delivered by Prodomax, an automation expert under the group.As a member of the Yina Group (a...

    2024-06-18
    See translation

  • Nuts: Adhere to embrace three-color laser technology, Krypton three-color laser optical machine to solve the speckle phenomenon

    Nuts is once again making waves in the home projection market with the launch of a new home projection product, Nuts N1 Air tri-color laser projector at a historically low price.In the increasingly "volume" home projection market, unswervingly layout of three-color laser nuts, breaking out of their own world.Laser projection permeability increases, nut is on topIn the first half of 2023, the home ...

    2023-09-05
    See translation

  • New technology can efficiently heal cracks in nickel based high-temperature alloys manufactured by laser additive manufacturing

    Recently, Professor Zhu Qiang's team from the Department of Mechanical and Energy Engineering at Southern University of Science and Technology published their latest research findings in the Journal of Materials Science. The research team has proposed a new process for liquid induced healing (LIH) laser additive manufacturing of cracks. By controlling micro remelting at grain boundaries to introdu...

    2024-03-15
    See translation

  • Germany's leading optoelectronics industry (Jenoptik) in the first half of the gold over 4.2 billion

    On August 9, local time, Germany's leading optoelectronics company Jenoptik released its 2024 second quarter interim financial results forecast. The financial data show that the company in the challenging market environment still shows strong growth momentum.In the first half of the year, Jenoptik achieved significant growth in revenue and earnings before interest, taxes, depreciation and amortiza...

    2024-08-15
    See translation

  • Israeli startup has developed a new laser powder bed fusion technology (SLS)

    Starting company 3DM from Israel has developed a new laser powder bed fusion technology (SLS) and recently released its first product. It is reported that the new technology developed by this young company established in 2016 will open up the possibility of new materials.3DM quantum cascade laserThe quantum cascade laser (QCL) stands out in the competition of 3DM in the SLS field. QCL was develope...

    2023-10-27
    See translation