Study of the GdrGaAs 110/system: interface and Schottky barrier formation at low and room temperatures

The interface formation upon deposition of Gd overlayers onto n-type GaAs 110.substrates was investigated at room and low 20 K, 100 K.temperatures by PE spectroscopy using synchrotron radiation, ultraviolet photoelectron spectroscopy UPS., Auger electron spectroscopy AES., and low energy electron diffraction LEED.techniques. Binding energy shifts of Ga 3d and As 3d levels at 300 K and 100 K were observed starting from the minimal Gd coverage ;0.03 ML.. It was found that band bending saturates only after metallization of the interface at 1–2 ML. It is argued that two different mechanisms are involved in the Schottky barrier formation: Fermi level pinning by defect states and metal-induced gap states. The Gd overlayers growth at low and room temperatures leads to reacted components showing up in Ga 3d and As 3d photoemission spectra at coverages G0.03 ML. All components reacted and unreacted.move to lower binding energies upon deposition of Gd. LEED studies at Ts20–300 K showed disordered interface structures at submonolayer and high coverage ranges. Temperature induced changes in the interface formation were observed as well. At 300 K the overlayer is cluster-like even at 0.03 ML while at 100 K and 20 K it is of Stranski–Krastanov and layer-by-layer types, respectively. q1999 Published by Elsevier Science B.V. All rights reserved.