DX Center-Like Trap in Selectively Si-Doped AlAs/GaAs Superlattices

Abstract
The behavior of a Si donor in selectively doped AlAs/GaAs superlattices(SLs) grown by MBE was investigated. It was found that Si atoms doped within ± monolayer from the AlAs/GaAs interfaces of the SL act as deep centers similar to the so-called DX center observed in mixed AlGaAs, while those confined in GaAs layers act as shallow centers. The fact led us to model the DX center as a Si donor having both Al and Ga at the second nearest-neighbor sites. The model consistently explains the DX center characteristics in mixed AlGaAs.