Effect of indium doping on the properties of GeSb phase‐change alloy

Abstract

The crystallization, electrical, and optical properties of indium-modified Ge 15 Sb 85 phase-change alloy have been investigated in this work. This alloy is used for solid-state memory applications. In 0.3 Ge 15 Sb 85 alloy exhibits an amorphous-crystalline transition temperature (T c ) that is slightly higher than that of Ge 15 Sb 85 alloy, which may lead to an improvement in its data retention time and thermal stability. AC conductivity measurements demonstrate that the conductivity of In 0.3 Ge 15 Sb 85 thin films is thermally activated with an activation energy of 0.32 eV. The optical transmission spectrum shows that the optical bandgap is E g ¼ 0.44 eV. The reported data reveals the presence of a Fermi level in the vicinity of the valance-band localized states. The capacitancevoltage measurements were performed for a sweep voltage from À20 to þ20 V at different temperatures. At low temperatures, the capacitance is electric-field independent and the crystallization is growth limited while the capacitance is electric field dependent at temperatures close to T c . The reported data show that modifying Ge 15 Sb 85 alloy with indium causes a significant increase in the electrical conductivity of the film that makes the capacitance always negative. These results promote the possibility of using In 0.3 Ge 15 Sb 85 alloy for phase-change memory applications with low switching voltage.ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Nonvolatile memory based on phasechange materials (PCMs) is one of the potential solutions for the key front-end wafer fabrication process technologies and the materials associated with these devices. PCM utilizes an amorphous to crystalline state transition that is accompanied by a drastic change in their electrical and optical properties. The reversible and rapid transformation between highresistance amorphous and low-resistance crystalline states makes phase-change random access memory (PCRAM) a promising candidate for the next-generation nonvolatile solid-state memory due to its high scalability, high endurance, high speed, low power operation, and low cost [1][2][3][4]. This technology has the potential to span a wide range of applications such as solid-state memory devices, computers, and space applications [5][6][7][8].One of the major challenges stated in the International Technology Roadmap for Semiconductors (ITRS) is obtaining a small scale, high-speed, dense, low-power, and embedded nonvolatile memory devices to replace FLASH memory by year 2018 [9]. The speed and the ability to retain information over many switching cycles strongly depend on the composition and structure of PCMs.

Investigation on the crystallization properties and structure of oxygen-doped Ge8Sb92phase change thin films

“…However, it is unfortunate that pure Sb-rich Ge-Sb has relatively low crystallization temperature and crystalline resistivity, implying poor thermal stability and high RESET current. Generally, doping is an effective method to modulate the switching properties of Ge-Sb binary alloys, such as N [18], Si [19], Al [20], Cu [20], Ag [21] and In [22], which can significantly improve the data retention and reduce the operation energy.…”

Simultaneously higher thermal stability and lower resistance drifting for Sb/In48.9Sb15.5Te35.6 nanocomposite multilayer films

“…The core of PCM was a phase change material based on chalcogenide compounds. 4 The working principle of PCM was to realize information storage via the reversible phase transition between amorphous and crystalline phase change materials. 5 The phase change material had high resistance in the amorphous state and low resistance in the crystalline state.…”

Study on the Performance of Superlattice-Like Thin Film V2O5/Sb in Phase Change Memory

“…The thermal stability of monolayer phase change films is inconsistent with the switching speed. 12 For instance, Sbrich phase change thin films Si-Sb-Te, 13 W-Sb-Te, 14 Ge 15 Sb 85 , 15 Sn 15 Sb 85 16,17 have faster crystallization speed but lower crystallization temperature. The newly developed superlattice-like (SLL) thin film has shown a great potential in accelerating the phase transition speed, lowering the power consumption and reducing the thermal crosstalk between nearby storage units due to its lower thermal conductivity.…”