25 January 2018
SMI receives SBIR award to evaluate bandgap tunability of gallium oxide by alloying with aluminium oxide and indium oxide on large-area substrates
© Semiconductor Today Magazine / Juno PublishiPicture: Disco’s DAL7440 KABRA laser saw.
Structured Materials Industries Inc (SMI) of Piscataway, NJ, USA – which provides chemical vapor deposition (CVD) systems, components, materials, and process development services – has received a US Department of Energy (DOE) Small Business Innovation Research (SBIR) award to evaluate the energy bandgap tunability of gallium oxide (Ga2O3) by alloying the material with aluminium oxide (Al2O3) and indium oxide (In2O3).
The ongoing effort is being conducted in collaboration with professor Lisa Porter and professor Robert Davis of Carnegie Mellon University (CMU). An assessment of Ga2O3 bandgap tunability is needed in order to increase the selectivity of sensors for the UVA, UVB and UVC bands, which is a focus of the project. The materials are grown using metal-organic chemical vapor deposition (MOCVD).
“Tuning the energy gap of Ga2O3 will establish an even broader range of applications for the material, such as graded heterostructures for optoelectronic devices, photodiodes (PDs) with tunable cutoff wavelengths, as well as optical filters with tunable transmission range,” believes SMI research scientist Dr Serdal Okur, who leads the firm’s Ga2O3 efforts. “Tuning the bandgap of high-quality materials will allow us to better assess optoelectronic properties… In2O3 and Al2O3 are good candidates to realize the bandgap engineering of Ga2O3. Additionally, we decided to use the MOCVD technique as it offers many advantages for ultimate device fabrication, including high growth rates, conformal deposition over device topography, and the capability for scale-up to high-volume production,” he adds.
“In our current DOE project, SMI will demonstrate gallium oxide (GO)-, aluminium gallium oxide (AlGO)- and indium gallium oxide (InGO)-based UV sensors that cover the whole UV spectrum,” says Okur. “In particular, these devices will be very important to detect UV photons from liquid Ar (argon) and Xe (xenon) scintillators, both at 128nm and 175nm, respectively, in particle physics experiments,” he adds. “SMI will further develop the MOCVD growth parameters and hardware to extend control of energy bandgap tuning of Ga2O3 with good-quality crystals. The company, in collaboration with CMU, will continue to explore the potential of large-area Ga2O3-based alloys with the intention of making the aforementioned sensors more economical and readily available than competing materials in UV sensing applications,” Okur continues.
The “extensive knowledge” of Porter and Davis in this area and CMU’s Nanofabrication Facility plays a critical role in the DOE project and related efforts, comments SMI’s president & CEO Dr Gary S. Tompa. SMI’s proprietary rotating disc oxide MOCVD reactor technology will be used in the project to demonstrate that Ga2O3 films can be deposited uniformly on large-area substrates. “We are pleased to showcase our in-house MOCVD reactor system capabilities for this Ga2O3 growth,” says Tompa. “Based on our past experience and industry standards, we will use a 13”-diameter susceptor for Ga2O3 growing in Phase II,” he adds. “We were also able to configure the platter for single-wafer (150, 200 or 300mm) or multiple-wafer (100mm or smaller) loads, which will help in evaluating the process.”