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Conference Paper

NREL/CP-5900-76122

July 2020

Dynamic Hydride Vapor Phase Epitaxy 

of III-V Materials for Photovoltaics 

Applications

Preprint

Wondwosen Metaferia, Elisabeth L. McClure, 

Kevin L. Schulte, John Simon, Dennice Roberts, 

and Aaron J. Ptak

National Renewable Energy Laboratory

Prepared for Compound Semiconductor Week (CSW) 2020

Stockholm, Sweden

May 17-21, 2020
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Conference Paper

NREL/CP-5900-76122

July 2020

Dynamic Hydride Vapor Phase Epitaxy 

of III-V Materials for Photovoltaics 

Applications

Preprint

Wondwosen Metaferia, Elisabeth L. McClure, 

Kevin L. Schulte, John Simon, Dennice Roberts, 

and Aaron J. Ptak 

National Renewable Energy Laboratory

Suggested Citation

Metaferia, Wondwosen, Elisabeth L. McClure, Kevin L. Schulte, John Simon, Dennice 

Roberts, and Aaron J. Ptak. 2020. Dynamic Hydride Vapor Phase Epitaxy of III-V 

Materials for Photovoltaics Applications: Preprint. Golden, CO: National Renewable 

Energy Laboratory. NREL/CP-5900-76122. https://www.nrel.gov/docs/fy20osti/76122.pdf. 
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Dynamic Hydride Vapor Phase Epitaxy of III-V Materials for 

Photovoltaics Applications 

Wondwosen Metaferia, Elisabeth L. McClure, Kevin L. Schulte, John Simon, Dennice Roberts, and Aaron J. 

Ptak

National Renewable Energy Laboratory, Golden, CO, USA

wondwosen.metaferia@nrel.gov

Abstract—We demonstrate the uniqueness of Dynamic Hydride Vapor Phase Epitaxy (D-HVPE) to deposit III-V 

materials for high efficiency and potentially low-cost photovoltaics applications. Unlike traditional HVPE, D-HVPE 

allows for the deposition of relatively complex heterostructures and devices at high growth rates. We recently achieved

record growth rates > 500 μm/h for GaAs and >200 μm/h for GaInP in our D-HVPE, and have not yet reached a growth 

rate limit for either material. We grew single junction GaAs solar cells at growth rates up to 309 μm/h without 

significant degradation of solar cell performance. We also demonstrate growth of Al-containing III-V materials in 

HVPE, a capability that makes D-HVPE more attractive for applications beyond photovoltaics. 

Keywords—D-HVPE; High growth rate; GaAs solar cell

I. DYNAMIC -HVPE

III-V semiconductors find wide applications in optoelectronics owing to their superior properties including

direct band gap, high electron mobility, their ability to be thin, flexible and light weight. For photovoltaics, III-V 

semiconductors demonstrated the highest efficiencies[1]. However, high material and manufacturing costs restrict 

III-V based solar cells to specialty applications such as space power and high concentration systems, despite their

many advantages over other solar technologies. To date, high quality III-V devices are grown by metal organic

vapor phase epitaxy (MOVPE). However, MOVPE uses expensive metal organic precursors and it is traditionally

a low growth rate technique with limited throughput. Hydride vapor phase epitaxy (HVPE) has recently reemerged

as a potentially lower-cost alternative to MOVPE for the growth of high-efficiency III-V solar cells. HVPE uses

low cost elemental group III precursors with high utilization efficiency and very high growth rates. Historically,

HVPE had two main difficulties. First was the difficulty of making the abrupt and low-defect heterointerfaces

necessary for the creation of complex, high-efficiency device structures due to its high growth rates. Second was

the difficulty of growing Al-containing materials necessary for the realization of devices that require Alcontaining layers, which traditionally were difficult using HVPE. Growth of Al containing III-V compounds such

as AlGaAs and Al(Ga)InP, in HVPE has been thought to be nearly impossible [2] due to highly unstable AlCl,

the Al source analogous to common HVPE metal chlorides, GaCl and InCl, as well as incompatibility with quartz

reactor parts. To circumvent these issues, we developed the ability to rapidly transfer substrates between growth

chambers to grow heterostructures with abrupt and high quality interfaces [3]. This process, termed Dynamic

HVPE (D-HVPE) is capable of producing III-V devices, with high efficiency GaAs single-junction(Fig. 1) [4]

and GaInP/GaAs tandem solar cells demonstrated [5] at high growth rates confirming high quality materials and

interfaces. By maximizing the source metal utilization and using uncracked hydrides (known as hydride enhanced

growth mechanism [6]), we demonstrated record growth rates in excess of 500 μm/h for GaAs and 200 μm/h for

GaInP (Fig. 2) [4], [7]. We also developed the external generation of much more stable AlCl3, which does not

etch quartz, and successfully demonstrated controlled deposition of AlxGa(1-x)As and, for the first time ever using

HVPE, AlxGayIn1-x-yP (Fig. 3) [8].

In this presentation, we will give a general overview of D-HVPE in the development of high efficiency singlejunction GaAs cells at growth rates in excess of 300 μm/h and discuss the implication to increase device 

throughput. We will also show our recent results on the growth of Al-containing compounds, such as AlGaAs 

and Al(Ga)InP.

II. CONCLUSIONS

By growing high efficiency GaAs single-junction and GaInP/GaAs tandem solar cells by D-HVPE, we 

demonstrated the feasibility of potentially lowering the cost of III-V solar cells for widespread applications. The 

growth of high-quality material at high growth rate and the growth of Al-containing III-V materials by D-HVPE 

will open up new opportunities of the technique for various optoelectronics applications. 

[1] M. A. Green et al., Prog. Photovolt. Res. Appl.,27, 1, 3–12 (2019).

[2] J. S. Yuan et al., J. Appl. Phys., 57, 4, 1380–1383 (1985).

[3] J. Simon et al., IEEE J. Photovolt., 7, 1, 157–161 (2017).

[4] W. Metaferia et al., Nat. Commun., 10, 1, 3361 (2019).

[5] K. L. Schulte et al., IEEE J. Photovolt., 7, 4, 1153–1158 (2017).

[6] K. L. Schulte et al., Appl. Phys. Lett., 112, 4,042101 (2018).

[7] E. L. McClure et al., Submitted (2020).

[8] K. L. Schulte et al., ACS Appl. Energy Mater., 6(2019).

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. 1
Fig. 2. Growth rate as a function of (a) GaCl partial pressure for GaAs and (b) group III-chloride (GaCl+InCl) partial pressure for GaInP growth in DHVPE. 

500

400

300

200

100

 GaAs 

Growth Rate (μmh-1

)

3.0 x10 1.0 2.0 -3

PGaCl (atm)

N2 carrier gas

H2 carrier gas

TD = 650 oC

PAsH3 = 0.0108 atm

PHCl = 0.0021 atm

 (a)

200

150

100

50

GaInP 

Growth Rate (μmh-1

)

2 4 6 8 10 12

PIII (x10-3atm)

V/III = 3

(b)

Fig. 3. Transmission spectra of (solid lines) AlxIn1-xP and (dotted lines) AlxGayIn1-x-yP epilayers bonded to glass. The direct band gap energies 

indicated in the legend are extracted by fitting the linear region of the transmission spectra 

0.5

0.4

0.3

0.2

0.1

0.0

Transmission

2.0 2.2 2.4 2.6 2.8

Energy(eV)

 HD676(2.62 eV)

 HD682(2.59 eV)

 HD741(2.55 eV)

 HD663(2.12 eV)

 HD681(2.15 eV)

 HD675(2.19 eV)

Al0.56In0.44P

Al0.54In0.46P

Al0.53In0.47P

Al0.19Ga0.29In0.52P

Al0.19Ga0.32In0.49P

Al0.21Ga0.32In0.47P

Fig.1. Open-circuit voltage measured from GaAs solar cells as a function of growth rate.

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. 2