Considerable changes in crystallization process delivered by N doping in Te-free, Sb-rich GeSb binary alloy

Different crystallization process concerning N doping was shown in this study. In the crystalline phase of Sb-rich, Te-free GeSb alloy, only Sb crystalline phase was observed as hexagonal phase and Ge crystalline phase was not shown yet in our annealing condition which is 400 °C for 20 min with a ramp rate of 10 K/min. Moreover, as increasing the N doping contents, overall crystallinity was suppressed and the lattice parameters were increased slightly from 4.274 Å to 4.285 Å for ‘a’ parameter and from 11.360 Å to 11.496 Å for ‘c’ parameter. It needs 50 nano-seconds and 15 mW minimum to crystallize GeSb alloy via laser irradiation. The Avrami coefficients were 0.76635 for an un-doped GeSb alloy and 0.37607 in average for N doped GeSb alloys. These Avrami coefficients mean that the crystallization process is growth dominant for un-doped GeSb alloy and nucleation dominant for N doped GeSb alloy. However, our Avrami coefficient values are different to typical values as from ∼1 to 4 because of our experimental condition that is not conducted throughout an isothermal condition. Sheet resistivity difference between amorphous and crystalline phase was more than three orders and the final sheet resistivity of crystalline phase was increased with increasing N doping contents. The phase transition temperatures defined via differentiating the sheet resistivity curve using spline fuction was 315 °C for un-doped GeSb alloy and increased to 350 °C for N-doped GeSb alloy.