Heavily Si-doped GaAs grown by low-pressure metalorganic chemical vapor deposition using tertiarybutylarsine and silane

Abstract

Heavy Si doping was studied for low-pressure metalorganic chemical vapor deposition of GaAs by using tertiarybutylarsine (tBAs) as a group-V source and silane (SiH4) as a doping source gas. The Si doping efficiency was higher by one order of magnitude when tBAs was used instead of arsine (AsH3). The maximum electron concentration was 9.0×1018 cm−3, which is slightly higher than that obtained for AsH3 (5.9×1018 cm−3). The slight increase of the maximum concentration is considered to be due to a reduction of the carrier compensating center generated in high SiH4 partial pressure conditions. Generation of the electrical compensating center is assigned to be related with the carbon incorporation from alkylsilanes during growth.

Desarrollo de células solares de doble unión de GaInP/GaAs para concentraciones luminosas elevadas (Development of GaInP/GaAs dual-junction solar cells for high light concentrations).

“…Therefore, the explanation for the increased carrier concentration with higher temperatures appears not to be in this direction. In fact, the results presented in [Chichibu92] show a similar dependence of the electron concentration with growth temperature for experiments carried out with TBAs and AsH 3 , using SiH 4 as silicon precursor. Another hypothesis is that the chemical reactions involved in the decomposition of DTBSi in the presence of AsH 3 , include intermediate steps where SiH 4 is generated among other elements, which appears not to be the case with TBAs [Leu98].…”

“…However, it has a critical problem consisting in the fact that the maximum electron concentration achievable is only around 1•10 19 cm -3 . As shown by SIMS measurements, the Si atoms continue to incorporate into the GaAs material for higher Si-precursor fluxes, but the electron concentration achieved does not increase but rather decreases [Chichibu92]. There exist several explanations for this behaviour.…”

“…In general, the carrier concentration obtained increases as the growth temperature increases. For SiH 4 , the electron concentration achieved depends clearly on the growth temperature up to well above 600 ºC [Chichibu92]. For Si 2 H 4 and DTBSi, the dependence on the growth temperature is significant for temperatures below 610 ºC and much less pronounced for higher temperatures [Leu98].…”

“…, the generation of a compensating center related to the incorporation of carbon [Chichibu92], the formation of complexes or precipitates [Furuhata88],…”

Desarrollo de la tecnología de MOVPE para el crecimiento de semiconductores III-V : fabricación de células solares para concentraciones luminosas elevadas

“…Tiene la ventaja de que difunde poco es GaAs pero, en cambio, tiene la limitación de que sólo se pueden obtener dopajes por debajo de 5•10 18 cm -3 , ya que a partir de ese nivel, el Si sigue incorporándose al cristal pero deja de ser activo suponiendo una disminución del dopado. Este efecto se ha corroborado mediante SIMS para muestras de GaAs dopada con Si utilizando diferentes precursores, entre ellos SiH 4 [Chichibu92] y Si 2 H 6…”