Growth of high quality Er-Ge films on Ge(001) substrates by suppressing oxygen contamination during germanidation annealing

Solid-state reactions between Er and Ge (001) under different processing conditions were investigated. Under normal rapid thermal processing (RTP) in high-purity N2 ambience, the Er-Ge film formation was 'contaminated' with Er2O3 even at low temperature annealing. Ti capping of Er films before RTP delayed Er2O3 formation with the Ti cap acting as a sacrificial layer for the Er underneath. Vacuum annealing of Er films significantly reduced Er2O3 formation even after higher temperature annealing. High quality Er-Ge films can thus be formed through solid-state reaction of Er and Ge if oxygen contamination from annealing ambient during RTP is controlled. The Er-Ge phase had low sheet resistance values averaging 3 to 4 Ω/sq. ErGe1.8 was formed from the solid-state reaction between Er and Ge(001) in vacuum.