Inelastic electron tunneling spectroscopy of MgO$_{x}$F$_{y}$ barriers

Recent development in TMR junction with MgO barrier attracts a great deal of attention. It is reported that the junctions with MgO barrier exhibit higher TMR with lower RA value. Combined with the spin-transfer switching that has been demonstrated, the future MRAM architecture will to incorporate the MgO barrier TMR junctions. The~ device parameters for MRAM will require the RA value of about 100 $\Omega -\mu $m$^{2}$, corresponding to about 1 nm thick MgO barrier layer. In order to understand the electrical properties of MgO barrier, we have fabricated Mg/MgO/Mg tunneling junctions as the function of oxidation time of the Mg metal layer. These Mg/MgO/Mg cross-strip junctions are deposited using stencil masks without a vacuum break, and the size of junction area is about 130 $\mu $m by 160 $\mu $m. When measuring d$^{2}$I/dV$^{2}$-V, namely the inelastic tunneling spectroscopy, we observed the peaks correponding to MgO bonds, indicating that the MgO barrier is a stable and good insulator. Using the IETS measurement technique, we will present the interface properties between the ferromagnetic electrode and the MgO barrier layer.~Moreover, we will report on our MgO$_{x}$F$_{y}$ tunnel barrier made by our fluorine-doping method.