Monolithic integration of InGaAs n-FETs and lasers on Ge substrate

Area of Science:

• Materials Science
• Electrical Engineering
• Optoelectronics

Background:

• Opto-electronic integrated circuits (OEICs) are crucial for high-speed communication.
• Monolithic integration of disparate semiconductor devices remains a significant challenge.

Purpose of the Study:

• To report the first monolithic integration of Indium Gallium Arsenide (InGaAs) channel field-effect transistors (FETs) with InGaAs/Gallium Arsenide (GaAs) multiple quantum wells (MQWs) lasers.
• To enable low-power and high-speed opto-electronic integrated circuits (OEICs).

Main Methods:

• Epitaxial growth of III-V layers on a Germanium (Ge) substrate using molecular beam epitaxy (MBE).
• Development of a Silicon-CMOS compatible process for fabricating InGaAs n-type FETs (n-FETs).
• Low-temperature processing (≤ 400 °C) to preserve the quality of InGaAs/GaAs MQWs for lasers.

Main Results:

• Achieved InGaAs n-FETs with a subthreshold swing (SS) of 93 mV/decade and an I_ON/I_OFF ratio exceeding 4 orders of magnitude.
• Demonstrated high effective mobility (> 2000 cm²/V·s) and low off-state leakage current in n-FETs.
• Realized room-temperature, electrically-pumped lasers operating at a 1.03 µm wavelength with a narrow linewidth (< 1.7 nm).

Conclusions:

• Successful monolithic integration of advanced InGaAs transistors and InGaAs/GaAs MQW lasers on a common platform.
• The developed Si-CMOS compatible process facilitates high-performance transistors and high-quality lasers simultaneously.
• This integration represents a significant milestone towards practical low-power, high-speed OEICs.