Superlattice-like Ga40Sb60/Sb films with ultra-high speed and low power for phase change memory application
In situ temperature-dependent resistance (R–T) wasperformed using a two-point-probe setup to obtain thecrystallization temperature by a TP 95 temperature controller (Linkam Scientific Instruments Ltd. Surry, UK). Thesamples were kept at different temperature for isothermalR–T measurements to estimate the data retention time andthe activation energy for crystallization (Ea) by theArrhenius equation. The optical band gap (Eop) wasderived from the transmittance spectra in the wavelengthrange from 900 to 2000 nm. The crystalline structures ofthe films were analyzed by X-ray diffraction (XRD). Thesurface morphology of the films was examined by atomicforce microcopy (AFM, FM-Nanoview 1000). The PCMdevices based on the [Ga40Sb60(5 nm)/Sb(4 nm)]5 thin filmwith a tungsten heating electrode of 260 nm diameter werefabricated by 0.18 lm CMOS technology. Between theGSS film and the top electrode, a 20 nm thick TiN film wasdeposited by direct current magnetron sputtering. Resistance–voltage (R–V) measurements were conducted usinga Keithley 2400 semiconductor parameter analyzer and anAgilent 81104A programmable pulse generator.
Hua Zou? Xiaoqin Zhu ? Yifeng Hu? Yongxing Sui ? Long Zheng ?Weihua Wu ? Liangjun Zhai ? Jianzhong Xue ? Zhitang Song