GaAs on Si epitaxy by aspect ratio trapping: Analysis and reduction of defects propagating along the trench direction

Abstract

The Aspect Ratio Trapping technique has been extensively evaluated for improving the quality of III-V heteroepitaxial films grown on Si, due to the potential for terminating defects at the sidewalls of SiO2 patterned trenches that enclose the growth region. However, defects propagating along the trench direction cannot be effectively confined with this technique. We studied the effect of the trench bottom geometry on the density of defects of GaAs fins, grown by metal-organic chemical vapor deposition on 300 mm Si (001) wafers inside narrow (<90 nm wide) trenches. Plan view and cross sectional Scanning Electron Microscopy and Transmission Electron Microscopy, together with High Resolution X-Ray Diffraction, were used to evaluate the crystal quality of GaAs. The prevalent defects that reach the top surface of GaAs fins are {111} twin planes propagating along the trench direction. The lowest density of twin planes, ∼8 × 108 cm−2, was achieved on “V” shaped bottom trenches, where GaAs nucleation occurs only on {111} Si planes, minimizing the interfacial energy and preventing the formation of antiphase boundaries.

Epitaxial growth of GaSb and InAs fins on 300 mm Si (001) by aspect ratio trapping

“…Increasing the GaAs thickness does not help preventing fin top rounding, as demonstrated in Ref. [21], where fins were 225 nm tall. The dark shades at the GaAs/Si interface are an indication of epitaxial stress due to the misfit dislocations, as well as threading segments and stacking faults which would annihilate at the oxide sidewalls if the GaAs fins were taller.…”

“…Experimental test structures were fabricated along the [110] direction using a "short loop" process flow, which included the formation of 180 nm thermal SiO 2 on Si, Samples were first cleaned with a wet HF process, and subsequently subjected to a wet NH 4 OH anisotropic etch, with the purpose of forming only preferential {111} Si facets at the trench bottom and obtaining a "V" shaped profile, as described in details in Ref. [21]. After the cleaning, wafers were loaded in the MOCVD tool and kept under vacuum prior to deposition.…”

“…The GaAs on Si template was grown at low pressure by using trimethylgallium (TMGa) as the group-III precursors, and tertiarybutylarsine (TBAs), as well as arsine (AsH 3 ), as the group-V precursors, as described in details in Ref. [21]. The GaAs buffer thickness was optimized to allow the formation of {111} facets and ensure an aspect ratio, for the partially empty trench, high enough to trap defects that could form at the GaAs/6.1 Å family layer interface.…”

“…In a previous paper, we explored the Aspect Ratio Trapping (ART) technique to deposit high crystal quality GaAs on 300 mm Si (001) by MOCVD, achieving an excellent control of the III-V/Si interface that allowed to suppress both TDs and APDs in the heteroepitaxial layer [21]. In this study, we extend the ART technique and develop an elegant strategy to deposit 6.1 Å family compound semiconductors on Si using a GaAs/Si (001) template with optimized thickness to allow confining defects generated at the GaAs/6.1 Å family layer interface.…”

Spatially correlated structural and optical characterization of a single InGaAs quantum well fin selectively grown on Si by microscopy and cathodoluminescence techniques

“…Selective epitaxy growth in trenches using the aspect ratio trapping (ART) method has been proposed and developed in the last ten years to trap defects at the sidewall of the trenches. [1][2][3][4][5][6][7][8] Very recently, this growth method has been used to realize an InP laser on 300 mm silicon substrate. 9 Another strategy called confined epitaxial lateral overgrowth 10 was proposed and used by IBM to realize InGaAs FinFET on Si.…”