InGaAsP-based uni-travelling carrier photodiode structure grown by solid source molecular beam epitaxy

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Materials Science

Background:

• Uni-travelling carrier photodiodes (UTC-PDs) are crucial for high-speed optical communication.
• Previous fabrication methods like Metal Organic Vapour Phase Epitaxy (MOVPE) faced challenges with unintentional zinc diffusion.
• Molecular Beam Epitaxy (MBE) offers superior growth control but traditional Gas Source MBE (GSMBE) involves toxic gases.

Purpose of the Study:

• To report the development of the first InGaAsP-based UTC-PD structure grown by Solid Source Molecular Beam Epitaxy (SSMBE).
• To characterize the performance of large-area, vertically illuminated test devices fabricated using this new method.
• To highlight the advantages of SSMBE for photodiode fabrication, specifically overcoming zinc diffusion and avoiding toxic gases.

Main Methods:

• Utilizing Solid Source Molecular Beam Epitaxy (SSMBE) for material growth.
• Incorporating thick InGaAsP layers (up to 300 nm) and an InGaAs absorber (120 nm).
• Fabricating and characterizing large-area, vertically illuminated photodiode devices.

Main Results:

• Achieved a responsivity of 0.1 A/W at 1550 nm.
• Demonstrated a -3 dB bandwidth of 12.5 GHz.
• Obtained an output power of -5.8 dBm at 10 GHz for a photocurrent of 4.8 mA.

Conclusions:

• SSMBE is a viable and advantageous technique for fabricating high-performance InGaAsP UTC-PDs.
• This method overcomes the critical issue of zinc diffusion prevalent in MOVPE.
• SSMBE provides the benefits of precise MBE control without the hazards associated with toxic gases in GSMBE.