In the present experiment, the samples (HOPG) were irradiated with Ar11+ HCIs at the fluence of 1014/cm2. SEM and AFM are used to observe the irradiated area. The different electron acceleration voltage was applied to observe the irradiated surface. In the SEM observation, the contrast of irradiated areas on the Si surface becomes darker than that of unirradiated area at the acceleration voltage of 1.0 kV or higher. For HOPG sample, it was necessary to lower the acceleration voltage down to 0.5 kV in order to obtain good contrast. However, for the samples irradiated by singly charged ions (SCIs), the fluence in the order of 1015~16/cm2 was necessary to obtain similar contrast as that of HCI irradiation. It means HCI has efficiency of 100 times as much as that of SCI for the production of SEM contrast. These effects were also found under the AFM observation. Therefore, compared to the singly charged ions, the HCIs are able to enhance the surface modification effectively.

doi:10.1063/1.3548367