Interface Formation and Electrical Transport in SnO2:Eu3+/GaAs Heterojunction Deposited by Sol–Gel Dip-Coating and Resistive Evaporation

The natural n -type conduction of tin dioxide (SnO 2 ) may be compensated by trivalent rare-earth doping. In this work, SnO 2 thin films doped with Eu 3+ have been deposited by the sol–gel dip-coating (SGDC) process, topped by a GaAs layer deposited by the resistive evaporation technique. The goal is the combination of a very efficient rare-earth emitting matrix with a high-mobility semiconductor. The x-ray diffraction pattern of SnO 2 :Eu/GaAs heterojunctions showed simultaneously the crystallographic plane characteristics of GaAs as well as cassiterite SnO 2 structure. The electric resistance of the heterojunction device is much lower than the resistance of the SnO 2 :2 at.%Eu and GaAs films considered separately. Micrographs obtained by scanning electron microscopy (SEM) of the cross-section showed that the interface is clearly identified, exhibiting good adherence and uniformity. A possible explanation for the low resistivity of the SnO 2 :2 at.%Eu/GaAs heterojunction is the formation of small channels with two-dimensional electron gas (2DEG) behavior.