We have investigated the effect of substrate temperature, TS, during growth by molecular beam epitaxy on the migration of Si atoms in δ- (or planar) doped GaAs and Al0.25Ga0.75As. Determinations of the extent of Si migration were made through analysis of quantum oscillations in the magnetoresistance and independently by using secondary ion mass spectroscopy (SIMS). Analysis of magnetotransport data in δ-doped GaAs samples indicates that there is negligible spread in structures grown at TS≤530 °C, while in structures grown at higher TS there is a measurable spread which increases with TS. For TS=640 °C, the Si spread is determ be = 180 Å. A similar analysis performed on the magnetoresistance of δ-doped Al0.25Ga0.75As samples reveals that the Si spreads further in Al0.25Ga0.75As than in GaAs (for a comparable TS). SIMS measurements performed on the same structures confirm these findings.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry