(Invited) Ge Surfaces and Its Passivation by Rare Earth Lanthanum Germanate Dielectric

Abstract

Germanium is considered to be an alternative channel material for advanced CMOS devices. Due to its small bandgap and high mobility, it can allow operation of devices at low supply voltage without loss of performance. The main obstacle for implementation of an all-Ge CMOS technology is the frequently observed underperformance of Ge n MOSFETs. Part of the problem could be that acceptor interface states in Ge lie in the low part of the energy gap close to the valence band so that the interface is easily charged negatively affecting transport in the n-channel. Additional and perhaps more severe complications arise from defects generated by poor quality oxides. Improving the quality of GeO2 large progress in Ge n MOS has been made albeit not without concerns about scalability to low equivalent thickness. Rare earth La germanate dielectrics exhibit good passivationg properties probably due to the suppression of harmful reactions of the dielectric with the substrate and maintain these good properties at low equivalent thickness suggesting a good potential for scalability.