Weapons Systems, AFC, Phase I
Electronic quality ferroelectric III-Nitride epitaxy for device heterostructures
Objective
To develop single crystalline epitaxial thin films and heterostructure of group III-IIIb-Nitride thin films for electronic device applications. The processes used should be scalable to 4-inch diameter wafer sizes or larger.
Description
Since 2019 there have been demonstrations of ferroelectric III-Nitride semiconductors with potential to impact future electronic and photonic applications due to their extraordinary properties. However, the only epitaxial growth process that produces single crystal thin films has been molecular beam epitaxy [1-3] and these films have already shown tremendous potential.
The alloys primarily focused upon so far are centered around incorporating scandium (Sc) in the AlGaN system. The opportunity for other group IIIb based alloys such as Yttrium has also been shown and may have merit to improve certain properties of the ferroelectrics [4,5]. Although the Army has started a MURI program based upon this subject, the use of MOCVD is complementary to that effort and requires novel precursors to grow the thin films [6,7]. Such MOCVD thin films would constitute the most easily manufacturable solution for larger wafer scale processes [6,7].
Thus, the aim is to develop them in parallel to some basic research for easy technology transition. Four inch or larger wafers are quite common to MOCVD reactors but are not possible in research grade MBE systems. The material science innovative research and development from this topic can enable useful product development at manufacturing for ferroelectric III-Nitride devices. Examples of this include high operating temperature electronic memory, high temperature electronic circuits, and integrated nonlinear optical photonic circuits for UV-visible wavelengths.
Phase I
Attain the appropriate precursors for AlScN and possibly AlYN or other alloy epitaxy to begin growth of thin films. Produce films lattice matched to GaN and possibly other substrates of interest to high performance wide-bandgap devices. Explore optimal growth conditions to produce single crystal films of high uniformity and crystallinity.
Assess optical and electrical quality of thin films including measurement of optical bandgap and transmission. Demonstrate HEMTs with electron mobility, sheet resistance, and sheet charge density on par with other reported AlScN/GaN heterostructures. Assess ferroelectric behavior including coercivity and temperature stability. Specific metrics for these results should aim to replicate those achieved with MBE growth films. However, phase I would only be the first stage at this goal with demonstrations of ferroelectric performance mainly being delegated to phase II.
The main goal of phase I is to try to achieve some ferroelectric behavior that shows promise for continuing the work to achieve state-of-the-art metrics in phase II. Measured polarization versus electric field curves with a characterization technique that shows polarization versus electric field hysteresis behavior via P-E, PUND or C-V techniques; however, specific metrics are not targeted in this phase I period. Progress on the crystallinity of the films, particularly at alloy compositions that match the lattice of the substrate will be assessed, particularly with GaN substrates.
Phase II
Continue pursuit of single crystalline epitaxial thin films and heterostructures for electronic quality III-Nitride ferroelectric based devices. Develop epitaxial processes relevant to 4” or larger substrates of interest to foundry scale manufacturing, particularly GaN (possibly others). Characterize ferroelectric behavior with PUND and capacitance-voltage measurements. Demonstrate remnant polarization > 15 micro-C/sq. cm. Fabricate devices to explore switching behavior aimed at electronic memory applications.
Pursue thin films that produce endurance of switching to > 1e7 cycles and over 600 C temperature of operation. Optical properties should also be considered for transmission, refractive index, and nonlinear coefficient assessments. Ideally, single transverse mode waveguide measurements showing < 1 dB/cm losses for wavelengths below the optical bandgap are needed for nonlinear optical functionality in integrated photonics. The second order nonlinear optical coefficients would also be of interest with a comparison to AlN and GaN.
Phase III
Produce epitaxial foundry services for in-house or customer developed electronic and photonic device regimes that make use of ferroelectric III-Nitride thin films. Collaboration with other research groups should ensue to make accurate comparisons with other epitaxial approaches toward high temperature electronic memory and polarization-controlled devices, including optical nonlinear frequency conversion.
Submission Information
For more information, and to submit your full proposal package, visit the DSIP Portal.
SBIR|STTR Help Desk: usarmy.sbirsttr@army.mil
References:
- Debdeep Jena, Ryan Page, et al. “The new nitrides: layered, ferroelectric, magnetic, metallic and superconducting nitrides to boost the GaN photonics and electronics eco-system,” Japanese Journal of Applied Physics 58, SC0801 (2019);
- Ding Wang, Ping Wang, et al. “Controlled ferroelectric switching in ultrawide bandgap AlN/ScAlN multilayers,” Appl. Phys. Lett. 4 September 2023; 123 (10): 103506.;
- D. Wang, Ping Wang, et al. “Ultrathin Nitride Ferroic Memory with Large ON/OFF Ratios for Analog In-Memory Computing,” Adv. Mater. 2023, 35, 2210628.;
- Stefano Leone, Isabel Streicher, et al. “Metal-Organic Chemical Vapor Deposition of Aluminum Yttrium Nitride,” PSS Rapid Research Letters. 17(10). 2300091 (2023);
- Ding Wang, Shubham Mondal, et al. “Ferroelectric YAlN grown by molecular beam epitaxy,” Appl. Phys. Lett. 17 July 2023; 123 (3): 033504.;
- Stefano Leone, Jana Ligl, et al. “Metal-Organic Chemical Vapor Deposition of Aluminum Scandium Nitride,” PSS Rapid Research Letters. 14 (1). 1900535 (2020);
- Isabel Streicher, Stefano Leone, et al. “Enhanced AlScN/GaN Heterostructures Grown with a Novel Precursor by Metal-Organic Chemical Vapor Deposition,” PSS Rapid Research Letters. 17 (2). 2200387 (2022)
Objective
To develop single crystalline epitaxial thin films and heterostructure of group III-IIIb-Nitride thin films for electronic device applications. The processes used should be scalable to 4-inch diameter wafer sizes or larger.
Description
Since 2019 there have been demonstrations of ferroelectric III-Nitride semiconductors with potential to impact future electronic and photonic applications due to their extraordinary properties. However, the only epitaxial growth process that produces single crystal thin films has been molecular beam epitaxy [1-3] and these films have already shown tremendous potential.
The alloys primarily focused upon so far are centered around incorporating scandium (Sc) in the AlGaN system. The opportunity for other group IIIb based alloys such as Yttrium has also been shown and may have merit to improve certain properties of the ferroelectrics [4,5]. Although the Army has started a MURI program based upon this subject, the use of MOCVD is complementary to that effort and requires novel precursors to grow the thin films [6,7]. Such MOCVD thin films would constitute the most easily manufacturable solution for larger wafer scale processes [6,7].
Thus, the aim is to develop them in parallel to some basic research for easy technology transition. Four inch or larger wafers are quite common to MOCVD reactors but are not possible in research grade MBE systems. The material science innovative research and development from this topic can enable useful product development at manufacturing for ferroelectric III-Nitride devices. Examples of this include high operating temperature electronic memory, high temperature electronic circuits, and integrated nonlinear optical photonic circuits for UV-visible wavelengths.
Phase I
Attain the appropriate precursors for AlScN and possibly AlYN or other alloy epitaxy to begin growth of thin films. Produce films lattice matched to GaN and possibly other substrates of interest to high performance wide-bandgap devices. Explore optimal growth conditions to produce single crystal films of high uniformity and crystallinity.
Assess optical and electrical quality of thin films including measurement of optical bandgap and transmission. Demonstrate HEMTs with electron mobility, sheet resistance, and sheet charge density on par with other reported AlScN/GaN heterostructures. Assess ferroelectric behavior including coercivity and temperature stability. Specific metrics for these results should aim to replicate those achieved with MBE growth films. However, phase I would only be the first stage at this goal with demonstrations of ferroelectric performance mainly being delegated to phase II.
The main goal of phase I is to try to achieve some ferroelectric behavior that shows promise for continuing the work to achieve state-of-the-art metrics in phase II. Measured polarization versus electric field curves with a characterization technique that shows polarization versus electric field hysteresis behavior via P-E, PUND or C-V techniques; however, specific metrics are not targeted in this phase I period. Progress on the crystallinity of the films, particularly at alloy compositions that match the lattice of the substrate will be assessed, particularly with GaN substrates.
Phase II
Continue pursuit of single crystalline epitaxial thin films and heterostructures for electronic quality III-Nitride ferroelectric based devices. Develop epitaxial processes relevant to 4” or larger substrates of interest to foundry scale manufacturing, particularly GaN (possibly others). Characterize ferroelectric behavior with PUND and capacitance-voltage measurements. Demonstrate remnant polarization > 15 micro-C/sq. cm. Fabricate devices to explore switching behavior aimed at electronic memory applications.
Pursue thin films that produce endurance of switching to > 1e7 cycles and over 600 C temperature of operation. Optical properties should also be considered for transmission, refractive index, and nonlinear coefficient assessments. Ideally, single transverse mode waveguide measurements showing < 1 dB/cm losses for wavelengths below the optical bandgap are needed for nonlinear optical functionality in integrated photonics. The second order nonlinear optical coefficients would also be of interest with a comparison to AlN and GaN.
Phase III
Produce epitaxial foundry services for in-house or customer developed electronic and photonic device regimes that make use of ferroelectric III-Nitride thin films. Collaboration with other research groups should ensue to make accurate comparisons with other epitaxial approaches toward high temperature electronic memory and polarization-controlled devices, including optical nonlinear frequency conversion.
Submission Information
For more information, and to submit your full proposal package, visit the DSIP Portal.
SBIR|STTR Help Desk: usarmy.sbirsttr@army.mil
References:
- Debdeep Jena, Ryan Page, et al. “The new nitrides: layered, ferroelectric, magnetic, metallic and superconducting nitrides to boost the GaN photonics and electronics eco-system,” Japanese Journal of Applied Physics 58, SC0801 (2019);
- Ding Wang, Ping Wang, et al. “Controlled ferroelectric switching in ultrawide bandgap AlN/ScAlN multilayers,” Appl. Phys. Lett. 4 September 2023; 123 (10): 103506.;
- D. Wang, Ping Wang, et al. “Ultrathin Nitride Ferroic Memory with Large ON/OFF Ratios for Analog In-Memory Computing,” Adv. Mater. 2023, 35, 2210628.;
- Stefano Leone, Isabel Streicher, et al. “Metal-Organic Chemical Vapor Deposition of Aluminum Yttrium Nitride,” PSS Rapid Research Letters. 17(10). 2300091 (2023);
- Ding Wang, Shubham Mondal, et al. “Ferroelectric YAlN grown by molecular beam epitaxy,” Appl. Phys. Lett. 17 July 2023; 123 (3): 033504.;
- Stefano Leone, Jana Ligl, et al. “Metal-Organic Chemical Vapor Deposition of Aluminum Scandium Nitride,” PSS Rapid Research Letters. 14 (1). 1900535 (2020);
- Isabel Streicher, Stefano Leone, et al. “Enhanced AlScN/GaN Heterostructures Grown with a Novel Precursor by Metal-Organic Chemical Vapor Deposition,” PSS Rapid Research Letters. 17 (2). 2200387 (2022)