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Evaluation on the Phase-Change Properties in W-doped Ge8Sb2Te11 Thin Films for Amorphous-to-Crystalline Reversible Phase-Change Device

비정질-결정질 가역적 상변환 소자용 Ge8Sb2Te11 박막의 W 도핑에 따른 상변환 특성 평가

  • Park, Cheol-Jin (Department of Advanced Chemicals and Engineering, Chonnam National University) ;
  • Yeo, Jong-Bin (The Research Institute of Catalysis, Chonnam National University) ;
  • Kong, Heon (Department of Advanced Chemicals and Engineering, Chonnam National University) ;
  • Lee, Hyun-Yong (School of Chemical Engineering, Chonnam National University)
  • 박철진 (전남대학교 신화학소재공학과) ;
  • 여종빈 (전남대학교 촉매연구소) ;
  • 공헌 (전남대학교 신화학소재공학과) ;
  • 이현용 (전남대학교 화학공학부)
  • Received : 2016.11.09
  • Accepted : 2017.01.31
  • Published : 2017.03.01

Abstract

We evaluated the structural, electrical and optical properties of tungsten (W)-doped $Ge_8Sb_2Te_{11}$ thin films. In a previous work, GeSbTe alloys were doped with different materials in an attempt to improve thermal stability. 200 mm thick $Ge_8Sb_2Te_{11}$ and W-doped $Ge_8Sb_2Te_{11}$ films were deposited on p-type Si (100) and glass substrates using a magnetron co-sputtering system at room temperature. The fabricated films were annealed in a furnace in the $0{\sim}400^{\circ}C$ temperature range. The structural properties were analyzed using X-ray diffraction (X'pert PRO, Phillips). The results showed increased crystallization temperature ($T_c$) leading to thermal stability in the amorphous state. The optical properties were analyzed using an UV-Vis-IR spectrophotometer (Shimadzu, U-3501, range : 300~3,000 nm). The results showed an increase in the crystalline material optical energy band gap ($E_{op}$) and an increase in the $E_{op}$ difference (${\Delta}E_{op}$). This is a good effect to reduce memory device noise. The electrical properties were analyzed using a 4-point probe (CNT-series). This showed increased sheet resistance ($R_s$), which reduces programming current in the memory device.

Acknowledgement

Supported by : 한국연구재단

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