Investigation of (Ge2Sb2Te5)1−xBix thin films by low frequency noise spectroscopy

Noise properties of the thin films (Ge
₂
Sb
₂
Te
₅
)
_1-x
Bi
_x
were investigated. Changing the amorphous film on the crystal structure was carried out by varying the voltage to 10 V on the resistor sample in the isothermal conditions at the constant temperature. The temperature varied from 290 to 420 K with 10 K increasing step. It has been shown that introduction of Bi influences the properties of the phase change memory materials. Bi introduction up to the 1 mass % in the amorphous film of Ge
₂
Sb
₂
Te
₅
reduces the low frequency noise power spectral density (PSD) values by two orders. Bi introduction more than 1 mass % leads to an increase in the values of power spectral density of the low-frequency noise in 100-150 times compared to the magnitude of the PSD in amorphous films. These phenomena may be used by an estimation of the Urbach parameter for the samples with different Bi content. The lowest Urbach parameter means that the sample has a more ordered structure.