Interface Formation and Electrical Transport in SnO_(2):Eu~(3+)/GaAs Heterojunction Deposited by Sol-Gel Dip-Coating and Resistive Evaporation

摘要

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.(percent)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.(percent)Eu/GaAs heterojunction is the formation of small channels with two-dimensional electron gas (2DEG) behavior.