Ultra-Thin Phase-Change Bridge Memory Device Using GeSb

Abstract

An ultra-thin phase-change bridge (PCB) memory cell, implemented with doped GeSb, is shown with <100µA RESET current. The device concept provides for simplified scaling to small crosssectional area (60nm 2 ) through ultra-thin (3nm) films; the doped GeSb phase-change material offers the potential for both fast crystallization and good data retention.

Evidence for electronic gap-driven metal-semiconductor transition in phase-change materials

“…1A). It crystallizes exothermally at 240°C and has been demonstrated to amorphize by thermal quench in a fast-switching device configuration at the nanoscale (18). The structure of crystalline GeSb is shown by X-ray diffraction to be the same A7 structure as pure antimony [supporting information (SI) Fig.…”

“…This is critical because during the phase-change process, along with the (orders of magnitude) jump in resistivity (3), there is a volume (density) change. The GeSb amorphous state is Ϸ8% less dense than the crystalline form (18), so, by Le Chatelier's principle, applying pressure (decreasing volume) should induce a change from the amorphous to the crystalline form. This will give us an isothermal path to induce the phase change.…”

Intrinsic constrains on thermally-assisted memristive switching

“…This imposes limitations on circuit design and feature size scaling, because of large current densities and thermal crosstalk. Therefore, it is important to study the intrinsic thermal properties of the device structure, which to date has only been done in the context of phase-change memory cells [4,19]. In those works, a specific cell structure of phase-change memory was analyzed using numerical simulations.…”

Thermal Stability of SiO2Doped Ge2Sb2Te5for Application in Phase Change Random Access Memory

“…[3,4] However, the high level of reset current (I res ) has been a major obstacle to the further scaling of PCRAM, because of the limited on-current drive capability of the cell transistor (< 0.5 mA/μm). There have been various investigations on the improvement of the switching performance of GST [5][6][7][8][9][10][11][12]. Although many improvements have been made in reducing I res , there still remain several issues to be resolved and one of them is the device reliability during the repeated switching cycles; degradation or failure of PCRAM devices, such as reset and set stuck, and compositional variation of phase change material, have been reported [13][14][15][16].…”