Transitions to Defective Crystal and the Amorphous State Induced in Elemental Si by Laser Quenching

Large-area, uniform amorphous layers have been formed on Si crystals by means of 2.5-nsec, 347-nm laser pulses. Computations indicate that amorphization at the resolidification interface occurs for isotherm threshold velocities of 18 m/sec on Si(001) and 15 m/sec on Si(111). The amorphous Si is impurity free and structurally similar to conventionally formed material. Below the amorphization velocity thresholds Si(001) reforms good single crystal while Si(111) gives twin defects down to {~}6 m/sec---a new defect transition.