Growth and Characterization of High Quality GaSb/GaAs Heterostructure by Metal-Organic Chemical Vapor Deposition Method for Post CMOS Application

Abstract

In this thesis we investigate the growth and application of GaSb/GaAs heterostructure for post Complementary Metal–Oxide–Semiconductor (CMOS) The misfit dislocations play a crucial role in the growth of the high quality Sb-based III-V material heterostructures which is of great interest for applications in the infrared optoelectronics and high speed low-power consumption electronics Due to the large lattice mismatch between the GaSb epitaxial layer and the GaAs substrate large number of defects generate in the epitaxial layer which vertically propagate to the active regions of devices thus leads to the non-radiative recombination and deteriorate the device performance These challenges can be achieved by the introduction of a novel epitaxial growth mode called interfacial misfit dislocation arrays (IMF) growth mode This growth mode enables the epitaxial growth of a high quality relaxed GaSb epilayer on a GaAs substrate without the creation of residual threading dislocations (TDs) The IMF achieves the flat surface through the creation of 90° misfit dislocations (MDs) at the GaSb/GaAs interface The structural electrical and optical characterization of the IMF-based material and fabricated devices all presented High resolution X-ray diffraction (HR-XRD) data and the dislocation network density is nearly correlated i e there is over 99% correlation between the location of one Lomer dislocation in the IMF array and its adjacent dislocations Further evidence is given that the interfacial treatments applied in the initial strain relaxation of GaSb/GaAs hererostructure the Sb interfacial treatment promotes the formation of strong Ga-Sb bonds on the surface of the grown island which effectively reduces the interfacial free energy and thus promotes the formation of 2D islands The GaSb epilayers on GaAs substrate were strain relaxed and exhibited enhanced electrical properties and optical properties Meanwhile the IMF growth mode has also been applied for the growth of high quality ultrathin-10nm-thick GaSb epilayer on GaAs substrate which is essential for ultrathin body MOSFET By optimizing the growth conditions the surface roughness of the ultrathin GaSb/GaAs heterostructure was reduced resulting in reduced carrier scattering and improved electronic properties Finally we have demonstrated the growth of a high-quality n-type doped GaSb/GaAs heterostructure based Metal–Oxide–Semiconductor Capacitor (MOSCAP) The n-GaSb MOSCAP fabricated shows exhibits excellent capacitance–voltage (C–V) characteristics with small frequency dispersion of approximately 2 8%/decade proving that high quality GaSb/GaAs heterostructure can be obtained using the proposed IMF growth mode The results demonstrate the potential of high-mobility Sb-based material on GaAs for post p-type channel CMOS applications in the future

Date of Award	2017 Jul 11
Original language	English
Supervisor	Shoou-Jinn Chang (Supervisor)