Heteroepitaxy and characterization of GaSb and InAs narrow bandgap semiconductors on Si

Abstract

Optoelectronics operating at the mid-infrared wavelength have been increasingly common in a wide range of areas including the defense industry, the automotive industry, and even natural gas detection. Narrow bandgap semiconductors have been the building blocks that have enabled these mid-IR technologies. A problem not unique to just narrow band gap semiconductors, but with most III-V semiconductors is the lack of semi-insulating, large sized, and lattice matched substrates. This prevents a wider deployment of these technologies mainly due to cost. To overcome these challenges, there has been significant effort in integrating III-V semiconductors on the Si platform. With this combination, III-V semiconductors benefit from a well-established and robust manufacturing platform while Si-based circuits benefit from increased functionality and performance. However, compared to GaAs/Si and InP/Si material systems, narrow bandgap semiconductor and Si heteroepitaxy is far less established. In this thesis, the heteroepitaxy of narrow bandgap semiconductors, namely GaSb and InAs, on Si is optimized and characterized to explore limitations and potential. Combining aspect ratio trapping with V-grooved patterned Si substrates, GaSb nanoridges were grown using metal organic chemical vapor deposition and characterized. By studying the heterointerfaces between GaSb and InAs, a GaAsSb-like interface at 500°C were determined to be the optimal conditions for InAs/GaSb heterostructures integrated onto Si. InAs/GaSb nanoridge gated resistors were fabricated and exhibited a current of 135 μA/μm at a Vds of 1 V and a Vg of 0 V. The growth of GaSb thin films onto various types of Si substrates, including V-grooved Si and GaAs on planar Si templates, yielded films of comparable uniformity in lattice parameters to the best grown using molecular beam epitaxy. The growth on planar Si templates yielded the smoothest GaSb films and have potential to serve as GaSb templates for infrared optoelectronics integrated on Si.

Date of Award	2018
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology