[1] Univ Buenos Aires, Fac Ingn, Dept Fis, Device Phys Lab Microelect, Buenos Aires, DF, Argentina
[2] Consejo Nacl Invest Cient & Tecn, CP, RA-1033 Buenos Aires, DF, Argentina
[3] Univ Buenos Aires, Fac Ingn, Dept Fis, Device Phys Lab Microelect, Buenos Aires, DF, Argentina