Sub-surface damage in indium phosphide caused by micromachining of grooves with femtosecond and nanosecond laser pulses

Grooves laser-micromachined in InP using 130 fs and 8 ns pulses with fluences ≈2 and 0.7 J/cm2 are investigated by cross-sectional transmission electron microscopy. At the fluence of 2 J/cm2, irradiation with both femtosecond and nanosecond laser pulses yield substantial resolidified layers with a maximum thickness of ≈0.5 μm. In contrast, at the fluence of 0.7 J/cm2, irradiation with nanosecond pulses leads to a layer of similar thickness, …