It has been an elusive goal for decades to combine the directly tunable bandgap of III–V compounds with advanced silicon fabrication technology on a CMOS platform to achieve a seamless integration of active photonic components with silicon electronics. Our nanophotonic projects focus on exploring scaled III–V active components monolithically integrated on silicon as emitters and detectors for applications in communication and IoT.

Integrating photonic devices

To integrate photonic devices, we are exploiting and expanding a fabrication technique called Template-Assisted Selective Epitaxy (TASE) invented at IBM [ More ]. This technique is ideally suited for photonic applications that require micrometer-scaled features, and that may benefit from the flexibility with regard to the choice of materials and growth sequence as well as from the high level of integration this affords. We want to exploit the potential for realizing different types of cavities on silicon and in-plane with silicon passives.

To integrate III–V-based optical devices, we have extended TASE and developed the virtual substrate and direct cavity approaches, which are two new ways to enable the monolithic integration of III–V material optical devices on silicon.

Microdisk laser integrated on silicon

Microdisk laser integrated on silicon. Scale 3 µm.

 

 

Direct cavity approach

In the direct cavity approach, III–V material is grown from a confined Si area of a Si wafer into a cavity. Growth first proceeds vertically, then it expands horizontally. The grown crystal has a mushroom-like shape. We used direct cavity growth to fabricate 1 μm large hexagonal disks that lase at around 835 nm at room temperature and feature an extremely high temperature stability.

From 10 to 300 K, the lasing peak shifts by only 6 nm from 830 to 836 nm, which translates to a remarkably high characteristic temperature of 1500 K — about one order of magnitude greater than usually found in III–V silicon photonic lasers. Lasing thresholds were found to scale with a reduction of disk diameter down to about 2 pJ/pulse [ More ].

 

VS approach

GaAs microdisk laser fabricate dusing the direct cavity approach.
(a) Cross section of microdisk (b).
(b) Top view of a GaAs microdisk 1 µm in diameter.
(c) Photoluminescence spectra of a GaAs microdisk at T = 80 K.

 

VS approach

Virtual substrate approach

In the virtual substrate approach, III–V material is integrated via a two-step templated growth process. First, a thin lateral µm2-sized virtual substrate is grown via TASE. Next, oxide is deposited and patterned to form a second template for the growth of the gain material in vertical direction from the virtual substrate. GaAs microring and disk lasers have been demonstrated with the virtual substrate approach emitting at 880 nm at room temperature [ More ].

We recently extended the fabrication process from binary GaAs to ternary InGaAs, which allows emission wavelengths above the Si absorption edge and hence opens the possibility of using Si for passives. We demonstrated the integration of InGaAs microdisk and ring lasers up to 200 K at emission wavelengths around 1150 nm [ More ]. The composition control in ternary compounds is more challenging, which can result in multi-crystalline structures.

 

VS approach

Direct cavity vs virtual substrate approach

Room-Temperature Lasing from Monolithically Integrated GaAs Microdisks on Silicon,”
S. Wirths et al.,
ACS Nano 12(3), 2169-2175, 2018.

Monolithic integration of III–V nanostructures for electronic and photonic applications,”
B. Mayer et al.,
Proc. SPIE 10349, Low-Dimensional Materials and Devices 2017, 103490L, 2017.

Microcavity III–V lasers monolithically grown on silicon,”
B. Mayer et al.,
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV, 105401D, 2018.

Monolithically integrated InGaAs micro-disk lasers on silicon using template-assisted selective epitaxy,”
S. Mauthe et al.,
Proc. SPIE Photonics 10672 Nanophotonics VII, 106722U, 2018.

Observation of Twin-free GaAs Nanowire Growth Using Template-Assisted Selective Epitaxy,”
M. Knoedler et al.,
Crystal Growth & Design 17(12) 6297-6302, 2017.

Towards Nanowire Tandem Junction Solar Cells on Silicon,”
M.T. Borgström et al.,
IEEE Journal of Photovoltaics 8(3) 733-740, 2018.

Dopant-Induced Modifications of GaxIn(1–x)P Nanowire-Based p–n Junctions Monolithically Integrated on Si(111),”
N. Bologna et al.,
ACS Appl. Mater. Interfaces 10(38), 32588-32596, 2018.

 

 

 

Photovoltaics

III–V semiconductors on Si tandem solar cells

 

Silicon-based solar cells are reaching their theoretical efficiency limit. This limit can be overcome by combining the current silicon photovoltaic technology with higher-bandgap materials, such as III–V semiconductors. However, material costs of III–V semiconductors is a limiting factor for mass production. Nanowires offer a cost-effective (minimum material consumption) solution without compromising absorption or performance.

The image at right shows a schematic drawing and a scanning electron microscope image of III–V nanowires grown with the TASE process on top of a silicon solar cell to form a multi-junction solar cell for next-generation photovoltaic technology [ More ].

SEM of III-V nanowires grown via TASW on a Si solar cell

Ask the experts

Kirsten E. Moselund

Kirsten E. Moselund
IBM Research scientist

Svenja Mauthe

Svenja Mauthe
PhD student

Heinz Schmid

Heinz Schmid
IBM Research scientist

Preksha Tiwari

Preksha Tiwari
PhD student

Noelia Vico Trivino

Noelia Vico Trivino
Post-doctoral researcher

EU projects

SiLAS

SiLAS
Towards a SiGe nanolaser.
A Horizon 2020 FET Open project 2017-2020.

Nanophotonics PLASMIC

PLASMIC
Plasmonically-enhanced III–V nanowire lasers on silicon for integrated communications.
H2020 ERC Starting Grant project under Grant Agreement Number 678567.

Nano-Tandem

Nano-Tandem
Nanowire based Tandem Solar Cells.
H2020, 2015-2019.

Publications

[1] “Microcavity Lasers on Silicon by Template-Assisted Selective Epitaxy of Microsubstrates,”
B. Mayer et al.
IEEE Photonics Technology Letters, 2019.

[2] “InP-on-Si Optically Pumped Microdisk Lasers via Monolithic Growth and Wafer Bonding,”
S. Mauthe,
IEEE Journal of Select Topics in Quantum Electronics, 2019.

[3] “Monolithic integration of III–V on Si applied to lasing micro-cavities: Insights from STEM and EDX,”
M. Sousa et al.,
Proc. IEEE 18th International Conference on Nanotechnology (IEEE-NANO), 2018.

[4] “Microcavity III–V lasers monolithically grown on silicon,”
B. Mayer et al.,
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV, 105401D, 2018.
DOI | Open access

[5] “Monolithically integrated InGaAs microdisk lasers on silicon using template-assisted selective epitaxy,”
S. Mauthe et al.,
Proc. SPIE 10672, Nanophotonics VII, 106722U, 2018.
DOI | Open access

[6] “Room-Temperature Lasing from Monolithically Integrated GaAs Microdisks on Silicon,”
S. Wirths et al.,
ACS Nano 12(3), 2169–2175, 2018.

[7] “Towards Nanowire Tandem Junction Solar Cells on Silicon,”
M.T. Borgström et al.,
IEEE Journal of Photovoltaics 8(3) 733–740, 2018.

[8] “Dopant-Induced Modifications of GaxIn(1–x)P Nanowire-Based p–n Junctions Monolithically Integrated on Si(111),”
N. Bologna et al.,
ACS Appl. Mater. Interfaces 10(38), 32588–32596, 2018.

[9] “Concurrent Zinc-Blende and Wurtzite Film Formation by Selection of Confined Growth Planes,”
P. Staudinger et al.,
Nano Letters 18(12), 7856–7862, 2018.

[10] “Observation of Twin-free GaAs Nanowire Growth Using Template-Assisted Selective Epitaxy,”
M. Knoedler et al.,
Crystal Growth & Design 17(12) 6297–6302, 2017.

[11] “Monolithic integration of III–V nanostructures for electronic and photonic applications,”
B. Mayer et al.,
Proc. SPIE 10349, Low-Dimensional Materials and Devices 2017, 103490L, 2017.

[12] “Template-assisted selective epitaxy of III–V nanoscale devices for co-planar heterogeneous integration with Si,”
H. Schmid et al.,
Applied Physics Letters 106, 233101, 2015.

[13] “IBM Scientists Present III–V Epitaxy and Integration to Go Below 14nm,”
IBM Research blog, June 18, 2015.