Self-limiting growth when using trimethyl bismuth (TMBi) in the metal-organic vapor phase epitaxy (MOVPE) of GaAs1−yBiy

MOVPE growth of Ga(AsBi)/GaAs using different metalorganic precursors

“…The parameters were chosen after careful optimizations of the growth conditions in order to optimize the quality of the Ga(AsBi) layers. As already figured out for continuous [10] and pulsed growth [11,13], the growth rate decreases with increasing Pp(TMBi). This is also observed for the continuous growth scheme used for the samples presented in this paper.…”

“…Experiments with the conventional precursors Triethylgallium (TEGa) and Trimethylbismuth (TMBi) as well as Tertiarybutylarsine (TBAs) show that growth temperatures of 375-400 1C are most suitable in order to realize high quality Ga(AsBi) structures, since a sufficient precursor decomposition is needed [10,11]. However, so far, only TMBi, TEBi, TEGa and TBAs/AsH 3 were used to grow Ga(AsBi) structures [10][11][12][13]. Indeed, it has been reported [10] that the Bi fraction is limited to about 7% in this temperature regime.…”

“…This leads for example to a decreasing growth rate if the Bi-precursor partial pressure is increased while the Ga-precursor partial pressure is kept constant. It has been suggested that the decreasing growth rate is caused by a surface passivation with methyl groups resulting from the TMBi [13]. Because of these methyl-groups the TEGa molecule or one of its dissociation products is no longer able to connect to the surface and will not be fully decomposed or will not reach the growth front, respectively.…”

Unexpected bismuth concentration profiles in metal-organic vapor phase epitaxy-grown Ga(As1−xBix)/GaAs superlattices revealed by Z-contrast scanning transmission electron microscopy imaging

“…However, they also revealed an unexpected and complicated concentration profile within each bilayer that deviated substantially from a square wave. The x-ray rocking curves obtained from these samples in the previous study 14 were fit this time to a function that better represented the shape of the profile observed in the STEM. The results provide insight into how Bi incorporates in Ga(As 1−x Bi x ) during growth.…”

“…Specifically, the concentration profiles confirm that Bi must have remained on the surface after the Bi precursor was turned off and was subsequently incorporated into the film during "barrier" growth, as discussed elsewhere. 11,13,14 Once the Bi on the surface is depleted, nominally pure GaAs grew for the time remaining in the barrier growth step.…”