Congruent Growth of Cu2Se Thermoelectric Thin Films Enabled by Using High Ablation Fluence During Pulsed Laser Deposition

The importance of the laser ablation fluence in congruent growth of Cu2Se thermoelectric thin films during pulsed laser deposition was shown in this work. By using a larger laser ablation fluence, a more consistent composition between as-grown thin films and the target material has been realized in the pulsed laser deposition of Cu2Se films This is associated with the enhanced plasma shielding effect, which weakens direct laser-solid interaction when increasing laser fluence. Reducing the ablation fluence can obviously increase the amount of the copper deficiencies, due to more effective laser ablation of Se (higher vapor pressure) than that of Cu when the laser direct lasser-solid interaction becomes more efficient. Apart from tuning the ablation fluence, thermoelectric performances of as-grown Cu2Se thin films are further optimized as a function of the used argon background gas pressures. The maximum thermoelectric performance of the Cu2Se thin film can be obtained when using the highest ablation fluence (similar to 10 J/cm(2)) and a low argon background pressure(similar to 10(-1) Pa).