Facile Five-Step Heteroepitaxial Growth of GaAs Nanowires on Silicon Substrates and the Twin Formation Mechanism

Abstract

Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices.

Growth kinetics and morphological analysis of homoepitaxial GaAs fins by theory and experiment

“…where the incorporation dynamics is faster, so that material eventually diffuses away from the {110} facets toward the top, as indicated by the arrows. A similar behavior was already reported for NW growth in SAE by MOCVD 30,31 . The difference in growth rate for the two facets inherently depends on the material transfer from one facet to the other and is mediated by the surface diffusion.…”

Equilibrium crystal shape of GaAs and InAs considering surface vibration and new (111)B reconstruction: ab-initio thermodynamics

“…In this figure, the point where the slope of the line changes corresponds to the transition point of the reconstruction of each surface. By combining the equilibrium condition of equation (7) and the calculated chemical potential of As gas ( μ As ( Gas ) ) as a function of T and P As , the experimental growth conditions can be denoted as the shaded area for GaAs 6,8–11,17–19 in Fig. 1(a) and for InAs 12,13 in Fig.…”

“…The gas phase surrounding the surface of GaAs was considered a mixture of As 2 and As 4 molecules. The Ga atoms (and the In atoms in the InAs system) were not considered components of the gas phase because the partial pressure of the group III gases is usually over 10 times lower than that of the group V gases in the practical growth conditions for III–V crystals 6,8–13,17–19 . The chemical potential of the As gas phase, μ As ( Gas ) , was calculated as a function of T and P using DFT calculations.…”

“…Many attempts have been made to solve these problems, and it has been found that selective area growth (SAG) is one of the effective ways of suppressing the propagation of dislocations and cracks as well as lowering the density of the anti-phase boundary 4–7 . The III–V compounds grown via SAG is in the form of quantum dots 6,8–16 or nanowires 10,11,17 . Their crystal morphology changes depending on the temperature (T) and pressure (P) of growth conditions 10,11,18 .…”

Selective Area Epitaxy of GaAs Microstructures by Close-Spaced Vapor Transport for Solar Energy Conversion Applications

“…Taken together, these findings suggest that CSVT growth, even at large Δ T and high growth temperatures, likely occurs closer to equilibrium than MOCVD. Because the energy of planar defects scales with area, much higher densities of twin plane defects are found in MOCVD SAE nanowire arrays. , …”