Mechanistic studies of the CBE growth of (100) GaAs using the new precursor tri-isopropylgallium

Chemical-beam-epitaxy growth of indium-containing III–V compounds using triisopropylindium

“…The onset occurs some 100°C lower than is observed for GaAs growth performed using the gallium analogue TIPGa. 11 This observation is consistent with the current understanding 25 that minimum InAs/GaAs CBE growth temperatures are limited by surface ''site blocking'' by adsorbed hydrocarbon fragments and/or excess arsenic, with the hydrocarbon fragments and arsenic being less strongly bonded to InAs, as compared to GaAs, surfaces. 9 More important, the data also show that the onset of InAs growth using the TIPIn, source occurs nearly 200°C lower than observed for corresponding InAs growth using TMIn, again consistent with a lower desorption temperature for isopropyl compared to methyl radicals.…”

“…GaAs growth rates of 0.6 m h Ϫ1 at 540°C were used during layer growth, these being reduced to 0.1 m h Ϫ1 in order to perform the in situ growth MBMS experiments. 11 Substrate temperature measurement was carried out using infrared pyrometry, calibrated with reference to changes in the reflection high-energy electron diffraction ͑RHEED͒ determined surface reconstruction at a fixed group-V overpressure. 16 The InGaAs MBMS experiments were performed, as a systematic function of substrate temperature, by measuring the fluxes desorbing from the growing surface during alternate GaAs and InGaAs layer growth.…”

“…9 More important, the data also show that the onset of InAs growth using the TIPIn, source occurs nearly 200°C lower than observed for corresponding InAs growth using TMIn, again consistent with a lower desorption temperature for isopropyl compared to methyl radicals. 11 Further increases in T sub are seen to produce a steady increase in the desorbing indium alkyl species up to T sub ϭ520°C, at which point, elemental indium desorption becomes the dominant process. This latter process is also observed both for InAs growth using conventional MBE, 26 and corresponding CBE growth using TMIn.…”

“…Furthermore, modulated-beam mass spectrometry ͑MBMS͒ studies have indicated that the use of TIPGa generates a significant reduction in the substrate temperature T sub required to initiate GaAs growth ͑by 50 and 100°C, respectively, when compared to corresponding growth using TEGa and TMGa͒, primarily as a consequence of the increased desorption rate of the isopropyl radicals ͑as compared with that of ethyl or methyl radicals͒ from the growing surface. 11 In addition, a recent MBMS study of the presence of low-level concentrations of TMGa on the substrate temperature dependence of the TIPGa-generated GaAs growth rate has demonstrated that, below T sub ϭ500°C, the coincident TMGa flux significantly inhibits the TIPGa-GaAs growth process. 12 This is the first experimental confirmation of methyl group blocking of surface sites under CBE growth conditions.…”

Selective area epitaxy of GaAs using tri-isopropylgallium

“…A similar temperature dependence was reported for the growth of GaAs on nonpatterned wafers using TIPGa, and the growth rate reduction in this temperature range was attributed to the higher rate of desorption of di-isopropylgallium with increasing growth temperature. 10 However, in the selective growth temperature window (380-420°C) for our deep UV patterned substrate, the growth rate is reasonably high compared to the case of SAE using TEGa, where the rate apparently has to be signifi- cantly lower than 0.1 µm/h to maintain selectivity below 450°C. 3 The results shown in Fig.…”