We have investigated the nitrogen doping effect on phase transition characteristics and electrical property of nitrogen-doped GeSb (N-doped GS) thin films. The nitrogen gas flow rate changed from 0 sccm (GS(0)) to 6 sccm (GS(6)) during the deposition. The sheet resistance of crystalline state was increased from 2.6 to 5.1 ka"broken vertical bar/a- and thermal stability of amorphous was increased as nitrogen gas flow rate increased due to nitrogen doping effect. Moreover, the average grain size was decreased from 9.7 to 6.6 nm at 400 A degrees C as nitrogen gas flow rate increased. However, the crystallization threshold time and laser power of GS(6) were shorter and lower than GS(0) caused by lower optical reflectivity. Nitrogen-doped GeSb showed the possibility of low RESET power and high speed PRAM operation.