Imaging of diamond defect sites by electron-beam-induced current

• An EBIC method based on Ag-Schottky layer made on p-type diamond (001) surface is demonstrated.
• This method is shown to be powerful to visualize the sites of potential ‘killer’ defects.
• It is further suggested that the fabrication of high-yield Schottky devices may be possible with the use of the present EBIC method.

The method of electron-beam-induced current (EBIC) was used to visualize the defect sites on a p-type (boron-doped) diamond (001) film. For this purpose, an Ag-Schottky layer (~ 2 mm × ~ 2 mm × ~ 50 nm) was deposited on the oxygen-terminated p-type diamond (001) film and used as a source of EBIC signal. The signal current of EBIC image appeared to be as large as ~ 1200 times that of the incident electron-beam current and the difference range in image intensity was also large (1–1200). The observed EBIC images showed many kinds of signatures that are possible ‘killer’ defects for Schottky devices. In order to identify ‘killer’ defects in the EBIC image, an array of Ag-dots (~ 40 × ~ 50 μm2) was deposited on an oxygen-terminated p-type diamond (001) film and I–V characteristics were measured on 53 Ag-dots. The resulting I–V characteristics showed that 21 Ag-dots reside on ‘killer’ defects. Comparison between the EBIC image and the positions of Ag-dots residing on ‘killer’ defects showed that large dark dots in EBIC image correspond to the position of ‘killer’ defects. The number density of the large dark dots (i.e., ‘killer’ defects) was ~ 104/cm2 in the present sample. It is suggested that a high yield Schottky-junction device may be fabricated by avoiding these ‘killer’ defects by the use of EBIC.

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