Electro-Thermal Confinement Enables Improved Superlattice Phase Change Memory

Energy Efficient Neuro‐Inspired Phase–Change Memory Based on Ge4Sb6Te7 as a Novel Epitaxial Nanocomposite

“…A recent trend in designing high-performance PCM materials has led to multilayered structures and superlattices including Sb 2 Te 3 /GeTe, [14,17,19] Sb 2 Te 3 /Ge 2 Sb 2 Te 5 , [20] and Sb 2 Te 3 /TiTe 2 . [5,21] In such materials, alternating layers serve both as diffusion barriers (e.g., TiTe 2 ) and nucleation sites (e.g., Sb 2 Te 3 ) facilitating fast switching speed.…”

Atomic Layer Deposition of Sb2Te3/GeTe Superlattice Film and Its Melt‐Quenching‐Free Phase‐Transition Mechanism for Phase‐Change Memory

“…Subsequent studies, however, revealed a crystalline-to-amorphous phase-transition behavior in a similar SL structure, indicating the possible controversy in the switching mechanism. Different mechanisms such as enhanced thermal efficiency, [10][11][12][13][14] stacking fault [15] or strain-assisted transition, [16,17] and partial amorphization [18] have also been suggested in more recent works. Still, studies so far lack a detailed analysis of the crystalline state in the set state.Besides, in previous studies, physical growth methods, such as sputtering and molecular beam epitaxy used to grow the SL films, cannot grow conformal film on highly topographical surfaces.…”

Unveiling the Effect of Superlattice Interfaces and Intermixing on Phase Change Memory Performance

“…Figure b shows that an ∼7–8× reduction in I reset is achieved in 2/1.8 nm/nm SL-PCM (∼0.35 mA) compared to a control GST device (∼2.5 mA) of same BE diameter. The SL-PCM with more internal SL interfaces show lower I reset due to improved electro-thermal confinement originating from the higher number of vdW-like interfaces ,, that are maintained during device switching Figure c reflects that the lowest resistance state (LRS) and the highest resistance states (HRS) of the devices also increase with more SL interfaces pointing to higher cross-plane electrical resistivity within the SL due to additional vdW-like gaps. , Figure c also shows that a resistance on/off ratio of ∼100 is maintained for the SL-PCM (and GST PCM) regardless of the number of interfaces.…”

“…Recently, superlattice (SL) phase change materials with ultrathin alternating layers (e.g., TiTe 2 /Sb 2 Te 3 , GeTe/Sb 2 Te 3 , or GeSb 2 Te 4 /Sb 2 Te 3 ) have been reported to lower the switching current density ( J reset ), resistance drift coefficient ( v ), and switching time in PCM. ,− Low cross-plane thermal conductivity and high cross-plane electrical resistivity of the SL films generate electro-thermal confinement in SL-PCM, driving the energy-efficiency in such devices. ,− The electro-thermal properties of the SL materials stem from the van der Waals (vdW)-like interfaces within the SL, − which have also been studied in other material systems; , the vdW-like interfaces are qualitatively similar but weaker than in covalently bonded SLs such as SiGe. Thus, SL interfaces, in particular their interface density and their intermixing (i.e., loss of vdW-like gaps, stacking faults, and disordering), can play a key role in the SL-PCM device performance.…”