Crystalline GaAs Thin Film Growth on a c-Plane Sapphire Substrate

Abstract

Crystalline zinc blende GaAs has been grown on a trigonal c-plane sapphire substrate by molecular beam epitaxy. The initial stage of GaAs thin film growth has been investigated extensively in this paper. When grown on c-plane sapphire, it takes (111) crystal orientation with twinning as a major problem. Direct growth of GaAs on sapphire results in three-dimensional GaAs islands, almost 50% twin volume, and a weak in-plane correlation with the substrate. Introducing a thin AlAs nucleation layer results in complete wetting of the substrate, better in-plane correlation with the substrate, and reduced twinning to 16%. Further, we investigated the effect of growth temperature, pregrowth sapphire substrate surface treatment, and in-situ annealing on the quality of the GaAs epilayer. We have been able to reduce the twin volume below 2% and an X-ray diffraction rocking curve line width to 223 arcsec. A good quality GaAs on sapphire can result in the implementation of microwave photonic functionality on a photonic chip.

Nanoscale Gallium Phosphide Epilayers on Sapphire for Low-Loss Visible Nanophotonics

“…We suggest that the Al 2 O 3 (0001) surface is oxygen-terminated since the used substrate annealing temperature (700 °C) is rather low to induce any surface modification. , Due to the strength of Al–O and Ga–O ionic bonds, it is highly likely that Ga–O or P–O bonds are formed at the GaP (111)–Al 2 O 3 (0001) interface, which is consistent with the earlier studies on heterointerface formation in GaN/Al 2 O 3 , and GaAs/Al 2 O 3 . We assume that each Ga atom tends to be stacked in the center of anionic sublattice triangles above the unoccupied octahedral voids to minimize the electrostatic potential, as presented in Figure b.…”

Single crystalline Ge thin film growth on c-plane sapphire substrates by molecular beam epitaxy (MBE)

“…The preparation for the sapphire substrate before the growth is discussed in our previous reports. 16,17,19 Consequently, all sapphire substrates used in this work possessed an atomic step-terrace surface, consisting of one monolayer with 0.2-0.3 nm high steps and non-uniform terraces having widths of 200 nm to 300 nm. Prepared substrates are transferred to either (a) the group IV chamber for growth of Ge or (b) to the group III-V arsenic chamber for growth of an AlAs nucleation layer, before transfer to the IV chamber for growth of Ge.…”

“…AlAs as a NL utilizes both of its elements to bond with sapphire: Al from AlAs bonds to O while As bonds to Al enabling it to wet the sapphire substrate. 17 Moreover, AlAs has better lattice match with Ge making it more suitable as a NL for Ge epitaxy. Our approach was to examine the effect of a thin, 10 nm thick, buffer of AlAs grown at 700 °C in the group III-V chamber which is UHV connected to the group IV MBE chamber.…”

“…The growth details of AlAs on sapphire are described elsewhere. 16,17 After growth of the AlAs thin nucleation layer, the AlAs/ sapphire substrate was then transferred to group IV chamber through high vacuum transferred lines and subsequent growth of Ge (∼50 nm) at temperatures between 250 °C and 700 °C. Fig.…”

“…Together, they have the potential to enable faster data transfer rates than currently possible. The choice to investigate the sapphire platform is based on several advantages over current silicon technology, such as, (1) significantly greater immunity to the defects of space radiation, 16 (2) high index contrast for efficient waveguides, 17 (3) a nearly perfect thermal expansion match to group IV and III-V semiconductors for durability, 18 and (4) the flexibility to support the monolithic fabrication of both laser and photonic integrated circuit on one platform, allowing higher function at reduced cost. 19 However, the approach must deal with a significant mismatch in lattice type and lattice constant.…”