Electron and hole separation in Ge nanocones formed on Si1−xGex solid solution by Nd:YAG laser radiation

The photoelectric characteristics of Ge nanocone structures, which are formed on Si surfaces by Nd:YAG laser radiation, is reported. It is found that exposing the SiGe/Si structure to irradiation intensities as high as 1.0 MW/cm2 Nd:YAG laser base frequency, which corresponds to effective formation of Ge nanocones on SiGe solid solution, significantly increases the surface photovoltage signal. The photovoltage decays do not shorten significantly with irradiation, thus indicating the fact that laser irradiation technique used here is capable of preventing the generation of considerable amount of carrier traps and recombination centers in the SiGe/Si structure and nanocones. From photovoltaic evidence it is therefore inferred that the laser irradiation fabrication technique is capable of providing well-defined carrier separation pathways without deteriorating the quality of the SiGe/Si structure and nanocones. Therefore, this technique can provide a cost-effective means for producing more effective photodetection devices in the near infrared.