Intensification of the Hydride Vapor Phase Epitaxy Manufacturing Process for Solar Devices

Photovoltaics made of III-V compound semiconductors, especially in the form of multi-junctions, have demonstrated great conversion efficiencies [1]. However, their application is limited significantly by the expensive fabrication methods and materials. To address this challenge, hydride vapor phase epitaxy (HVPE) has regained research interest because of its intrinsically higher growth rate and lower precursor costs compared with other epitaxial growth methods. But the high growth rate and near-thermodynamic-equilibrium nature of this process also impose difficulties of producing large-area uniform wafer in a controlled way. The process needs to be geared into a more economic and manageable configuration to produce high quality products with stable properties at rapid throughput.

There are already a couple of practices applying the philosophy of process intensifications in this area. For example, through clever design, the compact horizontal reactor in [2] was capable of growing various III-V semiconductors (GaAs, InGaAs, GaInP, etc.) at high growth rates and depositing multilayers of those compounds in a controlled mode by manually operating transfer rod and shifting gas flow [2, 3]. Based on this reactor, an improved inline reactor was proposed [4], in which the growth method was adapted to sequentially deposit different layer of material on one wafer travelling through multiple reaction chambers separated by gas curtain. To further promote performance of process and product, we present novel alternatives to previous intensification techniques using new concepts in both equipment design and operation method. Computational modeling tools are used to verify design and operational strategies. We are expecting this work will not only aid the production of economically and industrially viable III-V solar cells, but also inspire more ideas to optimize other CVD processes that grow films with high cost-performance ratio.

[1] M. A. Green et al., “Solar cell efficiency tables (version 49),” Prog. Photovolt: Res. Appl., vol. 25, no. 1, pp. 3–13, Jan. 2017.
[2] K. L. Schulte, W. L. Rance, R. C. Reedy, A. J. Ptak, D. L. Young, and T. F. Kuech, “Controlled formation of GaAs pn junctions during hydride vapor phase epitaxy of GaAs,” Journal of Crystal Growth, vol. 352, no. 1, pp. 253–257, Aug. 2012.
[3] K. L. Schulte et al., “Metalorganic vapor phase growth of quantum well structures on thick metamorphic buffer layers grown by hydride vapor phase epitaxy,” Journal of Crystal Growth, vol. 370, pp. 293–298, May 2013.
[4] D. L. Young, A. J. Ptak, T. F. Kuech, K. Schulte, and J. D. Simon, “High throughput semiconductor deposition system,” US20130309848 A1, 21-Nov-2013.