Enhancement of thermal stability and device performances through XTe2/TaxSb2Te3-based phase-change heterostructure

Abstract

Phase-change heterostructure (PCH) devices with alternately stacked layers of phase-change materials (PCMs) and XTe2-based confinement materials (CMs) have been introduced to suppress the long transport distance of atoms during device operation. Although the PCH has yielded improvements in terms of the resistance drift, cycling endurance, and noise of phase-change memory devices, the issue of low thermal stability remains a challenge. Furthermore, only TiTe2 has been reported as an XTe2-based CM layer; therefore, the applicability of other materials must be demonstrated in PCH devices. This study entails an investigation of an XTe2/TaxSb2Te3-based superlattice-like PCH device, wherein a Ta-doped PCM and newly applied CM layers are alternately stacked to enhance the thermal stability and electrical properties of the device. The surface roughness of the optimized device was observed to be < 0.2 nm in both the amorphous and crystalline states. The XTe2/TaxSb2Te3-based PCH device operated at a low voltage (VSET ≈ 0.9 V and VRESET ≈ 2.0 V) with enhanced durability due to the low drift coefficient (ⱱSET ≈ 0.001 and ⱱRESET ≈ 0.002), long cycle endurance (<1.6 × 109 cycles), and high switching speed (∼1.1 V/50 ns). The results indicate that the proposed material configurations can be implemented to improve the overall performance of phase-change memory devices.