Band engineering at the GaAssingle bondAlGaAs heterojunction using ultra-thin Si and Be dipole layers: a comparison of modification techniques

The control of semiconductor interfaces is essential to engineer new material properties for device applications. In this article we have considered the use of ultra-thin (1 monolayer) interfacial Si and Be dipoles layers to modify the band discontinuity present at the GaAssingle bondAlGaAs heterojunction. Soft X-ray photoelectron spectroscopy (SXPS) was performed at the Daresbury synchrotron radiation source (SRS) on samples previously grown by molecular beam epitaxy (MBE). Detailed deconvolution of the As 3d core level spectra enabled the valence band modification due to the presence of the interlayers to be extracted. The results of this study indicate the potential of this method to induce large valence band-offset modification (+0.4 eV for Si and −0.52 eV for Be) due to the presence of the dipole layers. The effect of any near interface doping by the Si and Be layers was considered by solving Poissonʹs equation for these structures. Finally, the technique is compared to other band engineering methods, namely δ-doping and multi quantum barriers (MQB), to assess the potential and viability for use in real devices.