Real-time characterization of GaSb homo- and heteroepitaxy

Abstract

We examine the homo- and heteroepitaxial growth of moderately thick (∼700 nm) layers of GaSb with the objectives of optimizing growth conditions and determining the initial phase of heteroepitaxy on (001)GaAs. Real-time spectroscopic ellipsometry (RTSE) data show that the (001)GaSb surface degrades immediately in excess trimethylgallium (TMG), but both (001)GaSb and As-terminated (001)GaAs surfaces are stable in trimethylantimony (TMSb). The surface-dimer contribution to the optical-anisotropy (OA) signal of (001)GaSb is small and generally masked by structural (roughness) effects, hence it is not useful for determining surface stoichometry. However, we show that laser light scattering (LLS) data do allow the V/III ratio to be fine-tuned during growth to minimize macroscopic roughness. TEM micrographs show that our GaSb/GaAs heterointerface is relatively defect-free except for the necessary local accommodation of lattice mismatch. The initial phase of heteroepitaxy on (001)GaAs occurs here as a coexistence of separate regions of GaAs and GaSb.

Real‐time diagnostics for metalorganic vapor phase epitaxy

“…To illustrate capabilities I describe the results that we obtained for the heteroepitaxial growth of GaSb on GaAs by OMCVD, with surface roughness monitored by laser light scattering (LLS) at 632.8 nm and growth itself with an integrated broadband spectrometer that returns surface-anisotropy and general RCE data over a wavelength range of 240 to 840 nm at an acquisition rate of 4 Hz [16]. The OMCVD system is a vertical-flow reactor operating at a samplerotation rate of 20 Hz and a chamber pressure of 60 Torr, with reactants introduced to the growth chamber using H 2 as the carrier gas.…”

“…8 Shift of the 〈ε 2 〉 spectra that occurred when TMSb was introduced into the growth chamber (after Ref. [16]). …”

“…7 Record of the pixel at 4.44 eV, showing that no Sb incorporated until the AsH 3 flow was terminated (after Ref. [16]). …”

“…6 Record of heteroepitaxial growth of GaSb and GaAs as described in the text (after Ref. [16]). Fig.…”